I like my headcanons so here we go! Also, feel free to request headcanons about any character or ship in the description and I shall provide my thoughts-

o    If there isn't any salted caramel food available for consumption, Kunimi will start to sulk. It's inevitable.

o    Kindaichi asked pretty much everyone for advice when he wanted to ask Kunimi out but then Kunimi made the first move on him.

o    Kunimi realised he was in love with Kindaichi in their second year at Kitagawa, at a small fayre that happened near Kitagawa First every year. Kindaichi had bought him salted caramel ice cream, which Kunimi promptly managed to get on his face accidentally. When Kindaichi noticed, he wiped it off for Kunimi and that was when the gay set in.

o    Kindaichi realised he was in love with Kunimi at the same fayre, but they were on the ferris wheel. Kunimi got freaked out when the ride stopped and they were out the very top, so he clung to Kindaichi and that was when the gay set in.

o    They both wonder whether Kyoutani and Yahaba are trying to become replicas of Iwaizumi and Oikawa subconsciously. Sometimes, they speculate about it.

o    Kunimi calls Kindaichi in the middle of the night when he's scared or has a bad dream and Kindaichi will always answer.

o    Kindaichi likes to buy Kunimi lunch and will always give him his umbrella.

o    Kunimi's' love language is physical affection - nothing sexy, he will just go up to Kindaichi and cuddle him when Kindaichi is trying to do homework or something similar.

o    Kindaichi's' love language is acts of servitude. If he can help Kunimi in any way at all, he's already done it.

o    Makki and Matsun were confused when they found out they weren't already dating upon entering Aobo Josai.