A/N: A couple of notes: first of all, I've gone back and re-worked Chapter 4. It's the only chapter of the fic I've really been unhappy with, and I finally decided to go and fix it. I've expanded the context of Fuutarou's breakdown, making the reasoning more apparent. I did not change any core plot elements though - nothing that comes after the chapter is affected or changed. I think it's much improved - hopefully you do too!

Anyways, this chapter is mostly fluff, so enjoy!

Chapter 17

The Eye of the Storm

When I returned to my classroom, the whole room went dead silent as I entered. All of the various cliques were staring at me from the various parts of the room, each with their own varying intents. It felt vaguely like how I imagined a zoo animal must feel. I raised an eyebrow at them, attempting to give my best impression of an extremely unimpressed teacher, and after a few moments the quintessential hubbub of a classroom prior to class resumed in full force. I could definitely hear my name frequently muttered as I made my way to my desk, a fact which irritated me to no small degree.

As I sat down in my chair, I happened to catch out of the corner of my eye that Itsuki was staring at me. I turned to look at her, and she mouthed, 'explain?' to me. I mouthed back 'later', and she pouted in return. Our silent conversation was interrupted by the entrance of the teacher, and the resumption of lessons.

In the second half of the day, we had physical education, and so we all went to get changed. On the way to the gymnasium, however, Itsuki caught hold of me (metaphorically), and a walking interrogation began.

"So," she said, trotting beside me to keep up with my quick pace. "What happened?"

"I simply got into a bit of a verbal spat with an ill-mannered whelp," I said, attempting to suppress the memory. Now that I had calmed down, I was a little embarrassed by it, though I still stood by everything I had said.

"Uesugi-kun, what the heck does that even mean?"

I sighed, pulling up short. Itsuki kept walking for a moment, and then cut back to stand next to me. "Your tutor is not a very nice person."

"I know that already. I meant the details as to what you were arguing about."

"...Oh. So you already knew that I was arguing with Second Place-san."

"Uesugi-kun, at this point, probably fifty percent of the school is aware of it," Itsuki said. "By tomorrow, it will certainly be ninety percent. The thing that is unclear to me is the details, and also why."

"I... see."

"What happened?"

"Well," I began, "I was just having lunch on my own, minding my own business and studying, when your tutor decided to come sit at my table. He then proceeded to be somewhat of an ass, and very obviously try to pick a fight. I wasn't having any of it, but eventually he succeeded in his goal of pissing me off... and things escalated from there."

I resumed walking, and a moment later Itsuki accelerated to keep at my side.

She sighed. "I don't know what he was thinking."

"Bold of you," I said, a slight smirk on my face, "to assume that he was doing that."

"Doing what?"

"Thinking."

Itsuki laughed. Then, as we approached the changing rooms, she slowed down, presumably to diverge from my path and go to the girls' locker room.

"By the way, Uesugi-kun," she said as she began to depart, "You should probably be aware - you know how our classmates have this dumb idea that we are going out?"

"Indeed - unfortunately I've been frequently acquainted with their stupidity, much to my chagrin."

"Anyways," Itsuki said, "they have decided amongst themselves that the reason for your fight was a quarrel between love rivals, and that you were fighting over me. I thought you ought to be aware in case some of them ask asinine questions."

"Don't worry, all of their questions are asinine. I'm used to it," I said.

"Good."

"Also, have no fear - we weren't fighting over you," I said.

"I know that, but-"

"We were fighting over Yotsuba," I said.

Itsuki stopped dead in her tracks. She looked thunderstruck.

"Wait... what?!"

"Indeed, 'twas a rivals' quarrel."

"Since when were you and - What?!"

I looked her dead in the eye, and I managed to hold a deadpan look for about a five seconds, and then I started sniggering. Itsuki's look of pure bewilderment lasted for about two seconds longer: then it turned to annoyance as she realized I was messing with her, and she shook her head.

"You're an ass, Uesugi-kun."

"Ah, well," I said, shrugging. "I am what I am."

Then, as I walked into the changing room, I said over my shoulder, "You did come up though. Just not in that context."

"Don't just drop that as you leave!" Itsuki yelled after me as I closed the door, and I chuckled to myself.

It's the small things in life.

I changed clothes as quickly as I could, so as not to give my classmates a chance to pose any of the aforementioned asinine questions. After I had put on my gym uniform, I made my way into the gymnasium to find a small scattering of go-getters already present. One of them was Itsuki, who had an extremely grumpy look on her face; I decided to take pity on her, and atone for my sins by going over and actually explaining what had happened.

"That idiot!" she exclaimed after I finished describing the fight, perhaps louder than she had intended. "I don't know what he was thinking! I can't believe he thought the fact we were getting annoyed with him was some conspiracy on your part - he's just a terrible tutor!"

"Indeed."

"Also, thank you for defending all of us. I really appreciate it, and I'm sure the others will too when they find out about it."

"Yotsuba already knows," I said, shrugging. "Apparently she was eavesdropping on the fight."

"Really? That doesn't seem very Yotsuba-like..."

"She panicked."

"Ah. Nevermind. That does sound like her."

"Right?"

Our conversation was suddenly interrupted by the loud blast of a whistle.

"Alright kids," the substitute physical education teacher yelled, whistle somehow staying between his teeth as he spoke. "Today, we're gonna make yourun!"

There were collective groans.

"How far are we gonna have to run?" one kid asked, raising his hand.

"Until I say stop."

"When will you stay stop?"

"When yer spittin' up puke, blood, and yer guts. Any other questions? No? Alright, get to it, kiddos!"

I looked at Itsuki. She looked back at me. We both grimaced, and then rose to our feet.

Non-athletic people, unite! You have nothing to lose but your electrolytes.

The next hour was hell. By the end, both Itsuki and I were on the verge of collapse, though Itsuki was slightly the better for wear than I was. In that moment, I vowed that I would improve my cardiovascular health so as to avoid a similar suffering the next time our teacher took a turn for the sadistic.

Of course, I knew I was lying.

Obviously.

There were a few students who genuinely seemed on the verge of vomiting when we returned to the change room, and so I gave them a wide berth. I returned to my school uniform rather quickly, and made my way back to the classroom.

Idiots avoided. Success.

The remainder of the day passed quite quickly, and before I knew it, I was sitting on the couch in the Nakano apartment surrounded by various dips and chips, and studying with Yotsuba.

Or rather, I was trying to study with Yotsuba.

"Hey, Fuutarou-kun," Ichika said, reclining on the couch that was perpendicular to the one I was seated on. "I heard you got into a fight today. Care to share the juicy details?"

"Well, I-"

"I heard you got into a fistfight behind the shed near the school pool." Miku said quietly, sitting next to me. "Is that true, Fuutarou?"

"What?! Of course not! I-"

"I heard," Nino said from the kitchen, smirking, "that it was a lovers' quarrel. Ah, young love."

I rolled my eyes at her. "You just made that one up."

"Tch."

I turned back to Miku. "No, I didn't get into a fistfight with anyone. There may have been some mild scrapping-"

"That's basically a fistfight!" Ichika laughed.

"-but it simply amounted to the grabbing of a shirt. Nothing more than that," I finished firmly.

"Boo," Ichika whined. "That's less fun."

"Can we stop talking about this? Yotsuba and I need to study."

"That's even less fun, Fuutarou," Ichika said. "I wanted to hear that you got into a fistfight behind a Denny's. I wanted to hear about how you kicked their butts!"

"How violent of you," I said unenthusiastically.

"What, can't a girl want a little spice?" Ichika said, her trademark sly smile gracing her face.

"Alas," I said flatly, "you'll need to seek spice from another source. Like the habaneros that Nino will probably sneak into your food later."

"Hey! I wouldn't do that!" Nino protested. I simply looked at her, and after a moment she looked away.

"...to her."

"Excuse me?"

"I wouldn't do that to her. You're fair game though, Uesugi."

"Remind me not to eat or drink anything else you offer me," I said drily. Nino turned away and muttered something under her breath.

"Um... Uesugi-san, do you mind if we get back to work?"

"Sorry Yotsuba," I said, turning back around to face my study partner. "My bad."

"It's fine, I just wanna get as much done as possible."

Yotsuba looked back down, and I noted that she had a look of sheer concentration on her face, to the point where she seemed almost... distant. Like part of her mind was somewhere else, mulling over what she was studying and tuning out the rest of the world. I flipped my binder back to the schedule at the beginning, and frowned.

We're quite far behind. I'm really starting to get worried. Second Place-san sapped way more of her progress than I was expecting... not to mention the distraction from her sisters.

"Ah, Uesugi-san," Yotsuba said, looking up from her work. "We're switching locations starting tomorrow, right?"

The question snapped me out of my reverie, and I nodded.

"Yeah, my dad leaves tomorrow morning. So we'll start meeting at my place after that."

"I'm excited to see it!" Yotsuba exclaimed, a smile on her face.

"Uh... right," I said, feeling uncomfortable. "Just... be warned. It's much smaller than your apartment."

"That's fine," Yotsuba said, looking back down at her notes. "That just makes it more cozy."

Somehow, I can't shake this feeling of anxiety.

We spent the rest of the evening studying, and making at least decent progress. We were starting to close the gap caused by the session with Second Place-san, but I could tell already that we weren't going to stand a chance of making it, especially with another two sessions with him on the following Thursday and Monday. Our only hope was that Yotsuba would be able to pass the exams without having fully caught up on the material - we would have to shotgun over certain preliminary topics, and hope for the best.

That comes later though. For now, we need to give her as solid a foundation as we can.

When I got home that evening, my dad was in the middle of packing a small suitcase which I hadn't even known we owned. I got to work helping, and we soon had the suitcase packed and compressed enough to squeeze shut. We then put away the table, pulled out the futons, and went to bed - we had a very early start the next day.

Within minutes, both my father and Raiha were fast asleep. I, on the other hand, found myself laying in bed, a ball of anxiety welling up in my chest. Scenarios kept running through my head, ludicrous scenarios with minuscule odds of occurring - and yet I couldn't stop the tide of my mind bringing the thoughts crashing ashore. Images of Yotsuba with a vaguely disgusted look on her face. Images of a brief look of pity, followed by polite disinterest. Images of her politely offering to go study in the library instead, because isn't it a little cramped in here?

I knew that all of those were unlikely - but somehow, the fact that the odds weren't zero was enough to bring my heart rate up, and gift unto sleep legs with which dodge and weave, all in service of its plot to cleverly elude me. Distractedly, I noted from a detached part of my mind that whenever I got these feelings, this... ball of anxiety, Yotsuba had always surprised me with her warmth and her grace. The fact that I was incapable of extrapolating from the available data and assuming that everything would be fine seemed, to the rational part of my brain, a clear intellectual failing.

Alas, my limbic system didn't remotely give a damn.

I huddled down deeper within my futon, the tightness somehow relieving some of the tension in my chest. There was something comforting about hiding in a dark space, as though one were hidden in turn from the world and its ills.

It's going to be fine. You're being overly dramatic.

Idly, I wondered when I'd begun to become so anxious. Certainly it had been present before I met Yotsuba, but I had noticed it more ever since then. There were changes which had begun to take place in my day-to-day life that I quite liked, but this was definitely not one of them. It wasn't that she evoked stress in me - it was more that I was ill-accustomed to having to care about what someone thought of me. I didn't know to what extent it was rational to worry, which things could be elided over, and which errors were a step too far.

It was as though I had begun stretching a muscle that I'd not used in five years. It was no wonder that it was cramping.

At some point in my angst I must have fallen asleep, because I was suddenly being shaken by Raiha, and it was time to get up and get ready for the day. It was quite early, perhaps half past five in the morning. We all ate breakfast, and then we left the apartment to take my father to the train station.

When we arrived, my father began getting emotional.

"I'm a bit worried. This is the longest I've been gone since..."

There was a moment of silence, as we all filled in the blank in our heads.

Since my mother died.

"...in a while," he finished lamely, and I suddenly found myself chuckling despite myself.

"Relax," I said. "We'll be fine. It's only a week - and besides, Raiha's the one who does all the cooking anyways. With you out of the house, the water will be safe."

"The water?" My dad asked, confused.

"Will be safe. From being burned."

My father rolled his eyes, and then gave both Raiha and me hugs. With an almost tearful goodbye, he walked through the turnstile. He turned back at least twice more, both times with Raiha and me raising our hands to wave to him.

Then, he was gone, and Raiha and I were standing there alone.

"Well," I said, "shall we head home? We have a bit of time before we need to get you to school."

Raiha nodded silently, a bit of a sad look on her face. We began walking back to the bus, but I was mildly concerned by the dejected expression on my little sister's face. Suddenly, I was struck by a strong fraternal urge, and looked around us.

We're near a station... there should be something open this early...

"Hey, Raiha?"

"Hmm?"

"Dad left us a bit of money to, and I quote, 'treat ourselves'. Do you want to go to that coffee shop over there? I hear they do really tasty chocolate drinks with no caffeine in them."

"Eh? You want to... Eh?! Who are you, and what did you do with my big brother?" Raiha cried in shock.

"What?!"

"The Onii-chan I know would never want to spend money on sugary drinks!"

"You just seemed sad, so I-"

Raiha squinted her eyes and protruded her lips like she was attempting to scan the inside of my brain and read all of my innermost thoughts. On most people it would have looked quite ludicrous, but on her it was just vaguely adorable.

"Fine, I've perhaps - perhaps! - occasionally been spending an extra one or two hundred yen to buy drinks during the day in between classes," I sighed. "It's my greatest shame."

Raiha blinked. "If that's your biggest shame, Onii-chan, then you're doing pretty well."

"Look, do you want the frosty liquid sugar or not?" I scowled.

"I want the frosty liquid sugar," Raiha said, and as we walked towards the café, I noticed there was a slight spring in her step that hadn't been there before. Despite myself, a small smile crossed my face. We walked in through the sliding automatic door, and made our way up to the counter where a bored barista was standing. They put on a cheery face as soon as we got close and I ordered a small 'frappuccino' (whatever the hell that was) for myself and another for Raiha. She wanted one that had a strawberry flavour, while I ordered a caramel-flavoured one. We sat at a nearby table while we waited for our order to be completed, and I noticed Raiha was kicking her legs back in forth in subdued excitement.

I suppose this is a rare treat for both of us. Not that we'll be making a habit of it.

Suddenly, I heard my name called, and I popped out of my chair to grab the two cold drinks. I slid the paper wrappers off the two straws I was handed, and slid each into their respective 'frappuccino'. I then walked back over to Raiha, who at this point was practically bouncing in her seat. I bowed deeply and dramatically handed over the drink, and she happily took it. We started walking out of the café, and Raiha took her first sip.

"This is amazing! It's so sweet, and delicious, and-"

"Scrumptious?" I said, smiling slightly.

"I don't know what that means, but sure!"

We started walking towards the bus, both enjoying our treat. Mine was a bit too sweet for my liking, but Raiha seemed a lot happier, so I was hardly going to complain about such simple things as it having too much sugar. It was a small price to pay.

Well, they were fairly expensive, so I guess it's not such a small price to pay - but c'est la vie.

Suddenly, Raiha doubled over in apparent pain.

"Ahhhhhh my head hurts! What the heck?!"

"That would be what's colloquially known as 'brain-freeze'," I said sympathetically. "You should probably drink that a bit slower."

Raiha looked up at me, tears in her eyes.

"Onii-chan, it hurts."

"Try pressing your thumb against the roof of your mouth, it should help a little bit. The brain freeze is caused by the membrane in the roof of your mouth contracting from the cold. Warming it up again helps a little bit."

Raiha shoved her thumb in her mouth and pressed it against the roof of her mouth, and after a little while, it seemed to work. We began walking once she'd recovered to the point of being willing to move again. Her eyes still tearful, she looked back down at her treat with slight fear in her eyes.

"Onii-chan, my drink bit me. I'm kinda scared to drink it again."

"Take it slowly," I said as we arrived at the bus stop. "It's October, so it's not going to melt immediately - so take your time."

Raiha nodded wordlessly, and slowly, quietly sipped on her drink. We eventually got on the bus and made our way home; and by the time we stepped off, she was happily re-engaged with the strawberry drink. The skip was back in her step, and I felt a sense of relief at having successfully fulfilled my fraternal duties.

We had about another hour to relax and finish our drinks, and then I walked with Raiha to her elementary school. The whole way, she was talking my ear off about the latest episode of her anime that she had been watching. I couldn't quite follow the details, but I did my best to at least appear to be paying close attention. After dropping her off, I caught the bus to head to my own school.

As Itsuki had predicted, most of the school seemed to know about my argument with Second Place-san - but outside of my class, most people seemed to not particularly care. It was just a bit of an oddity to them, one to laugh about with their friends, and then forget. Frankly, I wasn't too upset about that. The fewer people who were gossiping about me, the better.

Throughout the day, however, the anxiety I had felt the night before continued to gnaw at my belly, rearing its ugly head whenever I dared to think about what was coming that evening. When I sat down for lunch with Yotsuba, it had gotten so bad that I felt driven to vocalize it. Yotsuba just seemed bemused, however.

"I don't really get it," she said, taking a big bite of her tonkatsu. "Issnobgdulafferall."

"Chew, then talk," I said, sighing to myself.

She swallowed, then shook her head. "It's not a big deal to me that your apartment is small."

"I guess I just have a hang-up about it," I sighed. "This is just me being dumb, sorry."

Yotsuba smiled. "No, if it's something you're worried about, I want to try and understand."

"Well... let me put it this way. See that table next to us?"

"...Yeah?"

"Ok, now see the table two over that way?"

"Yes."

"Alright, now, finally, see the tables across the aisle?"

"Yes...?" Yotsuba said, a hint of confusion entering her voice.

"That's how big our apartment is. All of it."

Yotsuba looked around at the tables again, and seemed to be pondering something. Then she turned back to me, and shrugged.

"Seems pretty cozy, then."

"I mean," I said, suddenly not sure how to proceed, "it's just... a pretty drastic departure from the kind of size you're used to."

"Actually," Yotsuba said, playing around with her food idly, "that's only a bit smaller than the apartment we used to live in. So it really doesn't bother me."

"...Eh?"

That was news to me. Yotsuba looked up at me, a confused expression on her face.

"What?"

"You lived in an apartment that small?"

"Yeah," Yotsuba said, tilting her head. "It was a few years ago though."

"But... you're rich rich. How on earth...?"

A mischievous look suddenly crossed Yotsuba's face. "Shi shi shi. You want to know all about my dark and tragic past, Uesugi-san?"

"You have a dark and tragic past?" I asked, suddenly marginally skeptical.

"Oh, indeed, Uesugi-san! It's practically right out of a Greek tragedy. A murky tale for the ages!"

"Is that so?" I asked, deciding to play along. "Pray tell, Yotsuba, what is your angsty backstory?"

"Well," she said, winking and putting her hand near her mouth in a reasonable affectation of a shady used-car salesman, "I'll cut ya' a deal, kid."

I sighed. "I don't like the sound of this. What's the deal?"

"I'll tell ya' all about my tragic backstory... iiiiiif you stop worrying about the size of the apartment."

I frowned. "It's not like I'm worrying about it intentionally, Yotsuba. That's not how anxiety works."

Yotsuba frowned back in turn. "Well, shoot. I was hoping that would work. Back to the ol' drawing board."

Something about the look of genuine disappointment on her face made me crack up - and despite myself, the ball of anxiety in my chest seemed to loosen a bit. Yotsuba grinned, as if she knew the effect her face had elicited... and perhaps she did. Perhaps it had been intentional.

After school ended that day, Yotsuba elected to come straight to my place instead of going home to her own for dinner. We walked together from the school to the nearest bus stop, since there was a task we needed to complete before we could return to Raiha's and my 'cozy' apartment - and that was to retrieve the aforementioned younger sister.

We idly chatted on the bus, Yotsuba as constant a stream of enthusiasm and cheer as usual. Any anxiety that was still in my chest was being actively suppressed by her energy, and I found myself chuckling at her jokes almost against my will. By the time we arrived at Raiha's elementary school, I had almost forgotten the oncoming introduction of Yotsuba to my home.

When we walked in the gate, Raiha ran out the front door, and hugged Yotsuba.

"Yotsuba-nee-chan! I'm so happy to see you!" she squealed.

"Ah, Raiha-chan, I'm so happy to see you too!" Yotsuba squealed in return, returning the hug twice-over. "You're so cute, I was so excited to see you again!"

I watched this... perhaps the best term for it was ritual, with a vague sense of amusement. It was, of course, an objectively good thing that my friend was getting along with my little sister - but I couldn't help but find funny the way they both expressed those feelings in such an over-the-top way.

"Are you ready to go, Raiha?" I asked my sister, who was still wrapped around Yotsuba.

"Mhmm!" she replied, her face buried in Yotsuba's stomach.

The three of us began walking together, Raiha in between us chatting up a storm. There was something... easy about the way we just strolled, Raiha holding hands with both of us and skipping along the sidewalk. At one point, Yotsuba glanced up from her intense conversation with my sister, and grinned.

"Hey, Uesugi-san, the way we're all walking... doesn't it look like we're Raiha-chan's parents?"

I rolled my eyes at her. "Not in the slightest."

She stuck her tongue out at me playfully. "This is nice though, we should do it more often."

"Which part? Walking home, or picking up Raiha?"

Yotsuba pondered this for a second.

"...Both? Both. Both is good."

I snorted, but then nodded my head. "I'd be fine with that."

Yotsuba gave me a small smile, and then was suddenly pulled back into her conversation by Raiha, who was intent on talking about their mutual interest in anime. I just listened, feeling vaguely content. As we walked, the cool October wind blew past us, sending the leaves on the ground flowing about in small eddies, tiny invisible vortices making them dance and sway in the air before gently settling back to earth.

Eventually, we reached our apartment, and it was only as I unlocked the door, Yotsuba and Raiha waiting behind me, that I suddenly remembered that I had been anxious about her coming over. It was far too late to worry, however, as I opened the door, and stepped into our small entryway. Taking off my shoes, I stepped into the kitchen, and then into the main room.

"Ah, see? I was right, it's cozy!"

Yotsuba's voice behind me took the anxiety that had momentarily flared up, slapped it in the face, told it had been very naughty, and then banished it into the murky depths of the ether from whence it had sprung. The sense of relief that coursed through my veins, despite rationally knowing that her words were coming, were enough to make me laugh.

"Eh? Uesugi-san, did I say something funny?" Yotsuba said, taking off her shoes and stepping into the main room.

"No, sorry. Don't worry about it. Feel free to sit - do you want some tea?"

"Sure, thanks!"

I put my school-bag down in the usual corner, and went to go put the kettle on. Raiha flopped down on the tatami mats that made up our floor next to the table, and patted the floor next to her. Yotsuba put her bag down, and sat next to Raiha.

"Don't worry, Yotsuba-nee-chan," Raiha said. "Onii-chan isn't like our dad - he won't burn the water."

Yotsuba furrowed her brow in confusion. "Wait, how can you burn water?"

"That's an excellent question," I said from the kitchen. "One to which I would dearly like to know the answer."

"He's magically terrible at cooking," Raiha said solemnly, with all indication that she was being entirely serious. "I think he was cursed by a god in a past life."

I got to work preparing our cups, but part of me was somehow in disbelief.

She's... actually in our apartment. This is weird. I'm having trouble processing it.

The fact that I was experiencing cognitive dissonance was, in and of itself, causing me cognitive dissonance.

Luckily, if one's name is not Uesugi Isanari, one does not require particular focus to brew tea, and so my mind being a thousand miles away (and also approximately three metres behind my back) had no quantitative effect on the quality of the drinks I was making. Within a few minutes, the tea had finished brewing, and I brought the cups over.

I handed Raiha and Yotsuba steaming hot mugs of tea, and then placed my own down. Yotsuba stared down at her mug for a moment and then looked back up at me.

"Uesugi-san..."

"Yes?"

"I'm touched."

Confused, I looked down at her mug. "What? What are you talking about?"

Yotsuba lifted it up to show me the mug. "I'm so glad you think I'm the world's number-one dad! I'm honoured."

Sure enough, the side of the mug read "World's #1 Dad", a present Raiha and I had gotten for our father about seven years prior for his birthday using our scant pocket change. I'd grabbed it without thinking, since it was one of the very few we owned.

"I promise you," Yotsuba continued, putting her hand over her heart. "I may have received this award now, but I'm not going to stay stagnant - I'm going to continue to grow, and become a truly amazing father one day!"

Beside her, Raiha started cackling. I rolled my eyes, but despite my best efforts, a grin crept onto my face.

"So, are you planning to do trials for the Best-Dad Olympics?" Raiha asked. "I'll cheer you on with everything I've got!"

"Steady there, Raiha," I said, shaking my head. "She needs to do well in the prefectural Best-Dad heats first."

Yotsuba clenched her hand in a fist in front of herself, staring down at it intently.

"Uesugi-san... Raiha-chan... I'll do my best!"

Then she took a sip of her tea, and sighed contentedly.

"Ah, tea worthy of the world's best dad," she said. "Amazing."

We sat, drank our tea, and chatted for about fifteen more minutes, and then Raiha got up.

"Yotsuba-nee-chan, what do you want for dinner?"

Yotsuba smiled up at her. "I'm happy with whatever you make, Raiha-chan!"

"You should make curry," I said. "Definitely curry. Yotsuba will love it."

Raiha frowned at me. "You're just saying that because you want curry, Onii-chan."

"Correct. Your point?"

"Do you like curry, Uesugi-san?" Yotsuba asked, turning to me.

I nodded. "Especially hers. Raiha makes really good curry - it's probably my favourite thing to eat."

Yotsuba nodded several times, almost as if pondering something to herself. Then she turned back to my sister.

"I want to have curry then, if that's ok with you!"

"Leave it to me!"

Raiha trotted into the kitchen, and I looked over at Yotsuba.

"As for you and I... we should probably get to studying."

A sombre look crossed Yotsuba's face, as though she had forgotten the main reason she'd come. "Yeah... you're right."

Raiha busied herself with making dinner, while we grabbed our school bags, pulled out our textbooks, and began to get to work. We started with math, which was still by far Yotsuba's weakest area. She'd come quite far from not even knowing what a variable was... but it was just that. Comparatively quite far. In absolute terms, she was barely off the start line.

All I can do is give her as much support as I can.

"Hey, Uesugi-san?"

"Hmm?"

"What's a 'cardioid'?"

I paused my work on the Frobenius method for solving ordinary differential equations, and looked up at her in confusion.

"You shouldn't be at cardioids yet - I don't even think they're on the midterms. Where is that coming from?"

"Well, I looked ahead to the section on geometry, and on the list of shapes, they listed a 'cardioid', but there's no picture or anything."

"They listed a cardioid...? The author was just having fun then, that's pretty esoteric."

"What is it though?" Yotsuba said, furrowing her brow.

I paused for a second, thinking how best to proceed. Then, I looked down at my empty tea mug.

"Ok, here, take this."

I handed her the mug, and she looked down at it for a moment. Then she looked back up at me, and smiled. Somehow, it reminded me of when I'd returned her own test to her.

"Thank you for the gift! I'll cherish it, Uesugi-san!"

I bonked her gently on the head.

"Idiot. Look into it, and slowly move it around. What do you see?"

"Tea dregs...?"

"Anything else?"

She stared into the cup, and then her eyes lit up.

"Oh! The light is making patterns at the bottom!"

"Yep. The shape in there is sometimes a cardioid."

"That's cool!" Yotsuba said, moving the mug around and staring at it in fascination.

"Yeah. You can write the equation for it using trigonometric functions and plane polar coordinates, but you're not even close to being there yet."

Yotsuba put the mug down. "I don't really have a good idea of the shape though. Can you draw it?"

"Sure."

I grabbed some paper, drew a coordinate-axis, sketched a basic cardioid, and handed it back over to her - and then realized my error when I saw the look on Yotsuba's face.

"Shi shi shi. What's this? Handing me something like this... Uesugi-san, you sly dog! How sneaky!"

I face-palmed, and reached to pull the paper back, but Yotsuba kept it out of my reach, sticking her tongue out playfully.

"Have no fear, Uesugi-san! I'll make sure to memorize this shape! Then, when I reach trigonometry, I'll have a big step ahead!"

"I cannot stress how much you don't need this thing for the midterms," I said, my voice strained. "On multiple levels."

"What did Onii-chan give you?" Raiha called from the kitchen over the sound of sizzling oil, presumably cooking some kind of side-dish.

Yotsuba quickly stood up, pulling the paper further out of my reach, and hustled over to Raiha's side. There was a quick moment of whispering, and then Raiha turned to look at me.

"Onii-chan, I thought you were studying - why are you passing Yotsuba-nee-chan notes with hearts on them?"

"It's a cardioid, it's a geometrically useful shape, and that was not my intention," I said, feeling surprisingly flustered. "Truly."

Raiha gave me a doubtful look, which I thought was deeply unfair given my repeatedly professed position on such subjects, but Yotsuba just laughed. She came back to the table, put the paper down, and returned to studying. After a moment of quiet indignation, I returned to Ferdinand Frobenius and his method.

About twenty minutes later, Raiha finished cooking, and we hurriedly cleared away our notes in order to ingest sustenance. My sister placed the curry in front of each of us, and then poured rice into bowls from our small rice-cooker. I took a bite of mine, and was immediately in heaven, the umami flavour seeping into my mouth.

Nino may be the better cook by far... but this is still my favourite food.

"Raiha-chan, this is so good!" Yotsuba exclaimed, shoving a spoonful in her mouth. After swallowing, she stared down at it in wonder. "I think this is even better than Nino's curry!"

"Don't let her hear you say that," I said, shaking my head. "She'll blow a gasket."

"Oh, good point," Yotsuba said. Then, she lowered her head, and whispered, "I think this is even better than Nino's curry!"

"Why are you whispering?" Raiha whispered.

"There are Ninos in the walls," I whispered as well. "She's always listening."

There was a moment of silence, and then Yotsuba and I both started laughing. Raiha, who had no idea what a 'Nino' was, looked back and forth between us, shrugged in confusion, and then dug into her curry.

After dinner, I washed the dishes while Yotsuba and Raiha sat and talked about anime. Their conversation was almost entirely unintelligible to me, and so I tuned it out, focusing on finishing the job of cleaning the dishware as quickly as possible. As I put the last bowl to drain, Raiha flopped on the floor, and I suddenly remembered something important that had completely slipped my mind.

"Raiha?"

She froze. "...Yes?"

"Do you have homework?"

"...Maybe?"

"What do you mean, maybe?"

"...I said what I said."

I turned to look at her, raising an eyebrow. She made eye-contact, maintained it for a moment, and then almost seemed to crumple.

"Ok, fine, I do. I'll go get it..."

Raiha trudged over to get her stuff, and then flopped back on the floor next to the table.

"I don't wanna study," she moaned. "Don't wanna."

"Dad's not here, so I need to make you do it."

"You're the one who makes me do it anyways!" Raiha complained.

"Yeah, but I doubly need to make you do it now."

Raiha let out a wordless groan, and just flopped around on the floor. Sometimes, she seemed mature for her age... other times, it was extremely apparent what her true age was.

"Raiha-chan, why don't you study with us?" Yotsuba said, smiling gently at her and patting the spot next to her. "We can do it together."

Raiha perked up at that, and sat back up to sit next to Yotsuba. I frowned at the disparate effects our words had induced, but then shrugged to myself.

It makes sense that she'd react differently to someone else, versus her older brother. Such is life.

I returned to my spot, and got back into the groove of things. Raiha's presence definitely slowed things down, in particular because whenever she had a question about something, she asked Yotsuba about it instead of me, bombarding her with questions about math, social studies, and kanji. At first, I wanted to step in and tell her to stop distracting Yotsuba - but all of the questions were met with equally keen answers, and I decided that it wasn't worth it.

If they both want to focus on that, I guess I shouldn't complain. Maybe it'll help spark some connections for Yotsuba. After all, the best way to learn something is to teach it.

At one point, Yotsuba frowned at her work, and looked up at me.

"Uesugi-san... can I get some help with this? I'm done with coupled systems of linear equations, and now I'm getting to something called 'quadratic polynomials'?"

"Sure, what's the question?"

"Uh... what are they?"

"The answer is 42!" Raiha chimed in, beaming.

"Thanks, Raiha," I said drily. "Very helpful."

"Doing my best!" she said, giving a little salute.

I started giving Yotsuba a verbal description of what a quadratic polynomial was, but as expected, she got confused fairly quickly. There was a difficulty increase when going from an exponent of one to an exponent of two; rather like the graph of a quadratic versus a linear function, now that I thought about it.

"I think I need to see a picture," she said, shaking her head. "I don't think the symbols are going to work right away."

"Alright," I said, frowning. "Let me just think for a moment about the best way to present this."

Then, I pulled out a piece of paper.

"Ok, come over here, I'll show you how quadratics work."

Yotsuba scooched around the table and sat next to me. As I drew a coordinate axis on the paper, and drew a simple parabola, I was quickly consumed by my explanation. I glanced back up at her periodically to make sure that she was following - and it seemed that with the graphical representation, she was grasping the concept a bit more easily. In order to confirm, though, I had her repeat the concepts back to me in her own words, and draw graphs herself.

We continued talking like that, drawing parabolas, writing their corresponding quadratic polynomials, and looking at how transformations changed the parabolas, for almost an hour. By the end, I was fairly confident that Yotsuba could sketch a parabola from a quadratic function, and transform it at ease. I decided that teaching how to actually solve a quadratic function was something that would need to wait for another day. There were other subjects we needed to worry about.

It was only as I made the conscious choice to not move on to the roots of quadratics that I noticed just how close she was.

Yotsuba was practically pressed up against my shoulder - only the barest of gaps separated us, perhaps a centimetre at most. She was leaning over to see the papers I'd been drawing on, and so her head was also extremely close, overlapping with my shoulder vertically. If she lowered her head, it would have been resting on my shoulder, though the vertical gap was a bit larger than the horizontal one.

She'd been in this position, more or less, for about an hour, moving back as needed when I turned to talk to her - but I hadn't even noticed how close she'd been. It had just felt completely natural. I frowned, staring back down at the paper.

Aren't I supposed to feel embarrassed about this or something?

Then I mentally shrugged. I'd never particularly been one to get nervous about such trivial things.

I shouldn't read into it too much. This is normal.

As I over-analyzed, Raiha suddenly let out a large yawn, covering her mouth as she did so. I check the time on my phone, and was shocked to see that it was already past nine.

"Ah, Yotsuba," I said, turning to face her just as she withdrew her head - which was lucky, because there would have been a chance of a collision. "What time did you need to head home?"

She frowned, looking at her phone. "I guess I can call a taxi whenever I need to, though I probably shouldn't stay much later. Besides, Raiha-chan looks like she needs to go to bed."

"Nooo, I can stay up," Raiha said blearily. "It's fine, you can stay Yotsuba-nee-chaaaa-"

Her words were interrupted by another large yawn.

"You," I said firmly, "need to go have your bath, and then get ready for bed. You're falling asleep over there, and you had a very early start today to begin with."

"...'kay," Raiha said sleepily. She got up, and made her way over to our small bathroom. I turned back to Yotsuba, and she smiled at me.

"Sleepy Raiha is adorable," she said happily.

"This is true," I said, smiling back. "Shall we pack up?"

Yotsuba nodded, and we both packed our textbooks away, though I left my notes on the table - I wanted to finish working on my understanding of the Frobenius method after Yotsuba had gone home. Then, she pulled out her phone, and called a taxi. When she was done making the call, she went to go put her shoes on.

"I'll wait with you," I said, getting up to join her. The two of us stepped out the door, and down the steps to the street. The October night air was cold, but the wind was weak, and so it was at least comfortable.

"Thanks for having me over, Uesugi-san," Yotsuba said. "I had a great time. Raiha's cooking was delicious!"

"Of course," I said, smiling slightly. "It may not have been quite as productive as being at your place or the library, but I'm glad you had fun - and thanks for doing this. It makes watching Raiha a lot easier."

"It's no trouble! She's a great kid, it's fun to hang out with her!"

"Yeah, she is," I said. "She really likes you - I'm really glad. It would be awkward if my sister hated your guts."

"Yeah," Yotsuba said, raising an eyebrow. "I wonder what that would be like. Sounds terrible."

It took me a moment to connect the dots, and then I snorted.

"Hey, come on, I don't think any of your sisters really hate my guts anymore."

Yotsuba's eyebrow remained lifted.

"Nino doesn't hate my guts, she only hates my liver."

"Your liver?"

"Yeah. You know, because it filters out whatever she sneaks into my food to poison me."

"Ah, I see," Yotsuba said. "That makes sense. Her nemesis lurks within your very body, Uesugi-san! Beware, or she'll rip it out one day to seize her foe and strike it down!"

"Are you trying to say Nino is going to do surgery on me? Or that she's just going to stab me?"

"Aye," Yotsuba said sagely, not answering the question. "Don't make her angry, laddie."

"Too late."

"Alas! Yer' doomed!"

"Unfortunately," I said, shaking my head and a more serious tone returning to my voice, "the things that I think will make her upset, and the things that do make her upset, seem to be only partially overlapping sets."

"Ah, well, that's just how it is sometimes. You'll figure her out, Uesugi-san," Yotsuba said with a shrug.

"I appreciate your faith in me," I said drily.

"I have tons of faith in you," Yotsuba said simply.

Her words resonated with me in a way that I wasn't expecting. To my surprise, I realized that I was touched.

"Thank you. That... actually means a lot."

Having said that, there was a feeling lurking in the back of my mind. Some sense that there was a second meaning to what she was saying - but I couldn't piece together what it was. It was like I was trying to put together a puzzle, and all I had were a few of the centre pieces.

It's nothing. I suck at psychoanalysis. Leave it alone.

A light shone around the corner, and then a taxi was pulling up in front of us.

"Same time, same place tomorrow?" Yotsuba said as she pulled open the door.

"Don't you have your session with Second Place-san tomorrow?" I said, frowning.

"Oh... right," she said, a look of disappointment on her face. "Well then... I guess the day after?"

"Sure," I said. "Sounds good."

"Goodnight!"

"Goodnight, sleep well."

Then the door closed, the car left, and I was alone in the cool night. I looked around me for a moment, shivered, and then made my way back to the door. When I went back inside, Raiha was still in the bath, and so as I took off my shoes and stepped back inside, the main room was empty. In the absence of other people... despite its small size, the place felt cavernous.

I walked back over to the table, and sat down to get a little more work done. Then, I looked over the other papers on the table, and frowned. Yotsuba seemed to have accidentally forgotten the notes on parabolas. I moved those pieces of paper over into a pile, so that I could give them to her the next day. As I surveyed the rest of the scattered notes, my frown deepened. She'd forgotten the useful notes, but had apparently packed up the completely useless sketch on optics and plane-polar coordinates.

She had taken the cardioid with her.

"Huh. Silly of her," I muttered.

Shrugging, I returned to studying.