As night fell over Japan, Tsukasa couldn't get Kagami out of her head. Even after spending most of the day together, she still felt like they were far away. They got lucky earlier, but showing any kind of affection at home, let alone making love, seemed like playing with fire. If anyone caught them at an inopportune moment, they would both be burnt to a crisp. It was a cruel irony. The place where she was supposed to feel safest had become a place of torment.

The only place Tsukasa didn't have to keep her sadness bottled up was her bedroom. It was there, with her face covered in the same shameful tears she had cried countless times before, that she made up her mind. As painful as it may be, she would pretend this weekend never happened. She had allowed herself one moment of pleasure after years of longing, and that would have to be it. She couldn't bear to think what might happen if word of their relationship got back to their parents. The only thing left to do was break the news to Kagami.

Once she was confident that everyone had gone to bed, Tsukasa slowly approached Kagami's room. The light was on, so she knew Kagami was still awake. She opened the door just enough to peek inside. "Sis, can I come in?" she whispered through the crack.

Kagami sat up and gestured for Tsukasa to enter.

Once she was inside, Tsukasa closed the door behind her, taking care not to make any noise. She crept over to the bed and swallowed hard as she tried to find the strength to get the words out. "I've been thinking about it, and I…don't think we can make this work."

"Make what work?" Kagami asked.

"You know, us being a couple. I meant all those things I said last night, but maybe we should just try to forget it all, for the family's sake."

"Is that really what you want, or do you just feel like we need to break this off?"

Tsukasa froze. She knew exactly what she wanted. If it were up to her, she and Kagami would be open about their love, and let the rest of the world think what they want. She still held out hope that they would one day kiss while surrounded by flowers, just as they had in her dream, but that seemed impossible.

Kagami sighed. "I know I've been indecisive about this whole thing. It's scary enough being a girl dating another girl. A girl dating her own sister would be even scarier. This shouldn't be a hard decision to make, and yet it is. It makes no sense."

"Maybe love isn't supposed to make sense," Tsukasa countered.

"Hmm, maybe so." Kagami put away the book that had been resting in her lap. "Do you want to sleep with me again tonight? We don't have to do anything else if you don't want to."

Tsukasa, having been talked off the ledge, nodded. For the second night in a row, she crawled into Kagami's bed and hugged her sister needily. "I know we've kissed a lot in the last twenty-four hours, but do you think we could have one more? You know, just to say goodnight?"

Kagami tilted Tsukasa's head up and granted her request. It was only supposed to be a single peck, but it lingered for a while longer. As their lips moved back and forth, Tsukasa could just barely feel Kagami's tongue lapping against her teeth, teasing her. She still thought it was too risky to escalate things further, though, so she didn't reciprocate.

When they were both satisfied, Tsukasa rested her head on Kagami's chest and sighed happily. Even if they didn't stay a couple, she would do anything to be able to spend more nights like this. Try as she might, she just couldn't resist her sister's loving embrace, and at least now they had an excuse if anyone asked about it. The steady beating of Kagami's heart quickly lulled Tsukasa to sleep.

The next day at school, Tsukasa happened to arrive a few minutes earlier than usual. She saw Konata staring off into space, looking a lot gloomier than her usual self. Tsukasa's feelings about her had always been complicated. Although she was a rival for Kagami's affection, they were still close friends who could have long conversations about nearly anything. It didn't bring Tsukasa any joy to see Konata in such a state. She went up to her and waved hello.

"She told you, right?" Konata asked.

"You mean what happened with you and Sis? I only heard her half of the phone call. How are you feeling today?"

"I'll be fine, I guess. The writing was on the wall for a while. And how is she taking it? I haven't heard from her since Saturday night."

Tsukasa needed to choose her words carefully. It wasn't like she could start off by saying that she and Kagami had hooked up, but if she said something obviously untrue, she knew Konata would see right through it. After all, she was a terrible liar. "It was rough at first, but I've been spending a lot of time with her, and now I think she's doing better."

Konata cracked a smile. "That's good to hear. Even though it didn't work out between us, I don't have any ill will towards her. There is something you should know about her, though."

Tsukasa was confused. She thought she knew everything there was to know about Kagami. What could Konata possibly know that she didn't?

Konata leaned in close and brought her voice down to a whisper. "I think she's a siscon."

It took a moment for the words to sink in, but when they did, Tsukasa's head started spinning. She took a seat in the chair next to Konata so she could keep listening.

"Kagami talks about you and your other sisters all the time. She once told me that seeing you naked in the bath was how she realized she liked girls. Sometimes she would even ask me to call her 'Sis' while we were alone. I get that you two care about each other, and I'm not saying you shouldn't spend time with her. I'm only telling you this because I don't want her to take advantage of you."

Sweat began to drip from Tsukasa's brow. "Yeah, about that. After Sis hung up, I went to comfort her, but I got all emotional, one thing led to another, and we…" her voiced dropped. "Don't tell anyone about this, but we kinda had sex."

Konata's eyes widened. "Oh my gosh. Tsukasa, I'm so sorry."

"No, it's not like that. It was consensual, but now things are really awkward between us. I don't know what to do."

At that moment, the teacher walked in. "Well, I can't help you there," Konata whispered quickly. "Just try to be careful, okay?"

Siscon. The word Konata had used to describe Kagami was stuck in Tsukasa's head throughout the morning's lectures. She vaguely knew what it meant: someone with an unhealthy fixation on their sister. Now she was questioning everything she and Kagami had done together over the weekend. Had it all been in service of a fetish, as opposed to genuine love? Was that the real reason why they still weren't officially a couple? For that matter, was she a siscon herself? All she knew was that she needed answers, and she needed them now.