He asks Kai to spend a day together, just the two of them, and Kai gives him this certain look, that's not quite a smile or a happy look in general, but it's not a frown either, just this thing between his default look and something vaguely happy. But Aichi kind of considers anything that's not a frown from Kai as a sign of happiness and when he nods, says that sounds like a nice idea, Aichi smiles at him and isn't really sure if the short smile on Kai's face is imagination or not (in the end, he settles for not).
The next afternoon, they meet each other at card capital. They're in their casual clothes, because it's normal to spend time with his friend and to want to do something together without their other friends, so there's no need to dress up. Aichi's heart beats really fast, though, and it probably has something to do with his coat, because it's too warm today and it makes him feel a little uncomfortable when they greet each other.
They don't stay at the shop for long, just buy some card packs, but don't open them right there and instead go to that ice cream parlour that's rather far away from the card shop. It wouldn't really be a day for the two of them alone, if they were at the same place they are like literally everyday, where all of their other friends are as well.
A table outside is free and they sit down there, pull out the card packs they bought, open them to see which cards they got. Then, they take a look at the other's cards and Aichi got some of the new Kagero cards, but gives them to Kai.
Of cause, Kai doesn't take them at first, saying they are Aichi's and he's got enough cards at home and everywhere, but Aichi insists on it as make up for Blaster Blade, so eventually, Kai takes them. They sit there for a while, chatting about their decks and Aichi tells Kai about their club and what happened at school lately and has Misaki-san already told you about this.
The time goes by way too fast and when the sun starts to set, they leave and Kai walks him home afterwards. When they reach his house, Aichi stops in front of his door and turns around to face Kai. Kai stops as well, looks at Aichi and raises his eyebrow. Aichi simply shakes his head, steps a little closer to Kai and looks at him. Kai's eyes soften almost immediately, but he also looks a bit confused.
Aichi tries to smile and his heart beats very fast, although it's late and colder than before. He softly puts his hands on Kai's shoulders and gets on his tiptoes. He's pretty sure that by now, Kai can probably hear his heart beating and he swallows a little, then slowly moves his head closer to Kai's until –
their noses bump together and Aichi's hears definitely skips a beat then, but he can feel Kai's warm breath on his own lips, somehow recognizes Kai's cheeks getting red. So he pulls away a little, looks into Kai's eyes, which lost their usual hardness.
Encouraged by the kind of gentle look in Kai's eyes, Aichi takes a deep breath and then moves closer once again, but this time also tilts his head a little to the side to avoid doing the nose thing twice in a row.
Their lips barely meet and he's sure it's not a kiss.
His lips just kind of touch Kai's and he doesn't actually press them on each other, just lets them touch and Kai doesn't move. Still, it feels nice and Kai's lips are really cold compared to his warm breath, but Aichi can feel them twitch and form something that might maybe be a smile. After a moment or two, he loosens the grip on Kai's shoulder and leans back once again.
Together, they smile.