So I watched the anime (52 episodes plus third semester final two episodes, though I believe those were OVA's) and never saw this pairing come true...legitly. I tried to make another story earlier, but it went nowhere so I restarted and this came to mind. If your reading this, I hopw you enjoy it!
'I've come to accept it.' Harima thought to himself, 'The unavoidable fact...I will never have a future with her. She's gone off with him, and here I am...in the middle of nowhere.'
"Welcome back." Itoko commented.
"I can't believe I'm here again!" Harima cried over his now ruined manga, "Damn it, now I have to redraw this page!"
"I thought you were going to be gone for a while." Itoko murmured as she took a sip of her drink.
"And I thought you would shut up!" Harima snapped before a gun was pointed at his head.
"What was that?" Itoko asked threateningly.
"I mean I decided not to abandon this year so here I am, how have you been?" Harima quickly replied politely.
"That's what I thought you said." Itoko hissed, "Oh, since this is your last year, why don't you start making up for the screw ups of the previous years?"
"Huh? Now what exactly are you getting at here?" Harima asked.
"Just saying." Itoko replied as she hid an envelope entitled "Master Plan" signed by an "A".
"Make up for screw ups." Harima muttered as he walked to class, "Who does she think she is?"
"Hey Hige!" a voice called out.
"What do you want Ojou?" Harima replied.
"Ms. Itoko told me that you had something to tell me." she replied.
"What? What would I hav-" Harima stopped himself in time, 'Wait, is this what Itoko meant? To make up for the mess I've put her through? Well...I guess I have put her through a lot the whole time I've been chasing after Tenma...' Harima snapped out of his thoughts to see Eri tapping her foot impatiently.
"Well? We don't have all day you know." She snapped.
"Uhh...yeah, actually...I'll have to get back to you on that." Harima replied, "I...don't have what I need."
"...ok?" Eri replied as Harima walked away, 'Doesn't have what he needs? What the hell does that mean?'
Lunch time came around and Harima had taken to the roof, however it was unusually crowded.
"So what the hell are you doing here?" Harima asked, "I thought you'd be with your friends."
"Get lost." Eri snapped as she tossed her water at him.
"Hey! I don't have to take that fr-"
"Look just Leave me alone!" Eri snapped.
'Fine.' Harima thought to himself as he began to walk away but stopped, 'Wait a minute...water. During our second year at the beach, the girls were to learn how to swim from us guys but...she walked in on me when I was changing so it got awkward. THAT'S IT!' "Ojou! Be here at the pool tonight, alone, and bring your swimsuit!"
"WHAT!?" Eri snapped as she slapped him.
"Ehh...that all sounded wrong didn't it?" Harima asked.
"Oh just a little!" Eri replied sarcastically.
"Look, just do as I said, I'll explain tonight." Harima commented as he pulled out his phone and began to walk away, "Right now, I've got to go pull a few strings. ...Hey Yakumo, I need to ask you a favor."
'Just why the hell am I here?' Eri thought to herself as she passed through the school gates, 'What is Harima planning? I wonder why he stopped himself from snapping back at me? ...and why the HELL AM I ASKING MYSELF THESE QUESTIONS!? Wait...swimsuit, pool, night time...he wants to swim with me? But I can't swim.'
"Hey, you actually came." Harima called out, snapping Eri out of her thoughts.
"Uhh...yeah." Eri replied.
"Alright, let's get started." Harima commented as he began to take his pants off.
"WHAT THE HELL ARE YOU DOING!?" Eri snapped.
"What? I'm not going to swim with my clothes on, I have shorts on too you know." Harima replied as he took off his shirt next.
"Wait, why are you doing this...whatever this is." Eri asked and Harima turned away from her.
"Well...Ito-er Ms. Itoko said something that got me thinking." Harima replied, "She said that since it's my last year, I should make up for my screw ups of the previous years. I didn't think much of it until I saw you today and I remembered everything that's happened...what you've done for me, and what I've put you through. The time you sprained your ankle to hide my baldness, the new years, literal, over the cliff incident, and of course the...uh...beach incident." Eri blushed.
"Don't ever bring that up again!" she hissed.
"Unfortunately for you, I have to." Harima replied, surprising her, "See, as far as I know, that's where I really started to make your life harder for you."
'You have no idea Hige.' Eri thought to herself.
"Not to mention that because of that, things got weird and I couldn't help you learn how to swim." Harima continued, "So to make up for all that I've put you through, I asked Yakumo to ask Hanai for help. Took some convincing but I had this set up so I'll teach you how to swim tonight."
"H-harima." Eri whispered as she began to undress and Harima jumped into the water. Once she was down to her swimsuit, Eri slowly stepped into the water, trying to get used to it, but she was suddenly pulled in and she quickly stood up. Luckily the water was shallow enough for her to stand in, but it was deep enough to reach her neck.
"Sorry, it looked like you needed a little push." Harima laughed.
"Harima." Eri growled, "I'll get you for that."
"Ok, ok that may have been uncalled for, sorry." Harima admitted, "Now, since you can still stand here, then here is where we'll start. give me your hands." Eri complied and placed her hands in his. "Alright, now kick off the floor and use my hands as leverage to pull your body up and flat against the water, then start to kick, but not too hard or you'll only tire yourself out." Eri did as she was told, except that when she tried to straighten out she lost her balance, panicked and only managed to chug down some pool water before Harima quickly pulled her up. "You ok?" he asked as she coughed.
"Y-yeah." Eri replied.
"Alright, let's try again." Harima commented, "Just try not to panic this time." Eri nodded and kicked off the pool floor, managing to straighten out against the water and she began to kick as Harima kept her afloat by her hands. 'Heh, I never thought I'd say this again, but she looks kind of cute.'
"Ow." a voice whispered followed by a small splash that was not made by either Harima or Eri. They quickly sucked in some air and dove, however Eri fell like dead weight with her back first and hit what appeared to be a rock at the bottom of the pool causing her to cry out in pain and loose the air she had.
'Oh crap,' she thought to herself as she slapper her hand over her mouth, 'I'm not going to last long now, but I can't go up either!"
10 Minutes ago
"Hey Akira, what are you doing out here so late?" Mikoto asked before a hand slapped over her mouth and pulled her off the road. 'What the hell!?' she thought to herself before noticing another figure hidden with them, 'Ms. Itoko? Wait, someone's coming...Eri?'
"Huh...I could've sworn..." Eri said to herself before she continued on her way, "I'm losing it." Akira waited until Eri was fully out of ears reach before letting Mikoto go.
"Why are you guys following Eri?" she asked.
"Well, we did have a master plan," Akira replied, "But Harima did something we didn't expect."
"...you lost me." Mikoto commented.
"We were trying to set up Eri and Harima." Itoko explained, "Now that Harima is over Tenma, it was the perfect chance, but like Akira said, Harima did something we weren't expecting."
"Come on, she's headed for the school." Akira called out. The three of them began to follow as quietly as possible until they reached the school's pool.
"The pool?" Mikoto whispered, "What the hell is- IS THAT HARIMA!? WHAT THE HELL'S GOING ON!?"
"Shh, he's saying something." Itoko whispered before leading them closer in order to overhear Harima's explanation of why they were there.
"That's...that's the nicest thing Harima's ever done." Mikoto commented when Harima finished his explanation, "But...what did he mean with...the beach incident? Must've been something bad considering how they acted that day."
"I didn't hear about it." Itoko replied.
"It's best if you don't know." Akira commented.
"You know what happened?" Mikoto asked.
"I was there and was able to save him from humiliation." Akira replied, "That's all I'll say on the matter."
"...ok...huh? Look!" Mikoto exclaimed as she pointed towards Eri in time for the three of them to see Harima pull her into the pool, "Smooth, trying to make amends and he pulls her into the pool against her will."
"She doesn't look too bothered by it." Itoko commented, "She's not attacking him in some way."
"So, what are we going to just watch until they leave?" Mikoto asked.
"Just about." Akira replied.
A few minutes passed and Mikoto began to play with a rock the size of her palm until something crawled out from under it and bit her hand. "OW!" she cried out as she pulled her hand away and sent the rock flying in the process.
"Shh! Damn, they heard you!" Itoko commented.
"Sorry." Mikoto replied.
'Crap, someone is either passing by or we were being spied on.' Harima thought to himself before looking over at Eri to check on her only to find that she had both her hands on her mouth, trying to keep the air in her lungs. 'Shit, how'd she loose that much air in such a short time!? No, no time to think about that, I need to find a way to help her before-" Eri's eyes began to close slowly as her body started to go limp. 'Damn, only one thing left to do!' Harima quickly brought her to him and pressed his lips against hers, allowing them to share his air. Eri's eyes shot wide open in surprise and relief before they slowly closed again. Unnoticed by them however, they had begun to float to the surface.
"Just how long can they hold their breath!?" Mikoto whispered.
"Well, they can't be down there much longer that's for sure." Itoko commented.
"OH, MY, GOD!" Mikoto shouted, not even trying to lower her voice. Akira and Itoko turned to see Harima and Eri surface while locked by the lips, apparently too distracted to hear Mikoto's screaming. Akira and Itoko acted quickly to silence Mikoto before they were discovered.
Eri felt herself and Harima surface, but even then neither decided to break the moment. If anything, the life saving lip lock had gone from a kiss, shortly after, to a full on make out session. Eri finally pushed lightly on Harima's chest and they slowly broke away, staring at each other for a few moments before the sound of a twig snapping shot them back to their situation.
"Ah, umm...uh...so...it's getting late," Eri commented, "and-"
"Yeah uhh...you made great progress..." Harima continued, "so let's call it a night."
"Yeah, sure!" Eri replied before they made their way out of the pool. Harima pulled himself out and quickly turned to help Eri out before they put on their clothes.
"Umm...Eri?" Harima called out once they were dressed, "If you want...we could forget about this-"
"No!" Eri interrupted, "I mean...I'd love it if you continued to teach me, Harima."
"Great!" Harima replied, "Uhh, I mean...do you want me to walk you home? Kinda dangerous out at night."
"...I'd love that." Eri replied before they left the school.
"Hey, if you don't mind me asking, what were you upset about earlier today?" Harima asked.
"You know, looking back, it was over something really stupid." Eri replied and Harima laughed.
The next day the students noticed two different things, one was that Eri and Harima didn't fight like they usually did, but instead got along. The other was that Mikoto had a smile, which said 'I know someone's secret', the whole day which was copied over to Tenma's face shortly after the first few minutes of class.