Quiet is the best way for Kenji to enjoy his birthday. Too much attention at any point is too much for his best friend, so Aone makes sure to stay quiet (not hard) and not remind anyone; not even his mother (she doesn’t need reminding), and lets the day happen like any normal day.
Save for arriving early with Kenji so they can open the clubroom together and set up the court. He catches them when they’re still changing; still the only ones in the clubroom though he knows they won’t be for long, because Koganegawa’s gotten more proactive about getting in as much training as possible.
So the middle blocker takes the opportunity while he has it, with a large hand gently touching to a shoulder to get Kenji’s attention. His fingers shift, then, slowly down his arm past his elbow and his wrist to grab a loose hold of his fingers. Aone’s other hand lifts as well, fingertips touching to the captain’s chin just so, just enough to guide it to where he wants it to be, so he can lean forward and press their lips together in what he’s sure is the most confident (only confident) kiss he’s ever been able to give his best friend with not even a trace of embarrassment to his cheeks.
And when he pulls away after a few lingering seconds, it’s not entirely. Just enough to break the contact, but close enough to still be able to feel the gently puff of each exhale. And when he speaks, his voice is low and quiet, in a way that fears breaking the silence more than anything, because the words come easier than words ever do.
He has never really liked making his birthday public - so, obviously, he never tells his team, and really, Aone only knows because they’ve been friends for long. He also knows, from years prior, that Aone’s mother will give him a gift after school, and that his own mother will probably get Kenji to invite him and Kenjirou to dinner. He doesn’t mind - Aone and Kenjirou get along well, and it’s never been a problem.
But - first, there’s the problem of school. They have early morning practice - which isn’t a problem of his, not at all. He loves this team, and he knows Aone won’t say anything about his birthday in front of them. He doesn’t need unnecessary attention, after all. He unlocks the clubroom, trailing in and dropping his bag near the locker he uses to store his things.
He feels a hand rest gently on his shoulder, and his eyes lift from his locker upwards to glance at his best friend. His fingers instinctively lace with Aone’s, a thinner hand fitting within a larger one, and he tilts his head a little. He lets himself be guided into a kiss, gentle and sweet. While kisses like this - or in general - would leave him flustered, this is one he takes wholeheartedly, leaning up into the other teen.
Aone pulls away, and he lets out a soft laugh, a smile rising onto his face. Of course Aone manages to give him the best gift, as always. He squeezes his hand, the one laced with Aone’s, and he leans up to press a chaste kiss onto the other’s lips.