headcanon that kyoutani has a tummy and he never really cared before, but he knew it wasn't really a pretty thing
one day he's cuddling yahaba and yahaba is casually stroking his tummy and tells him how he loves it. kyoutani is completely astonished because why would someone find that nice? and yahaba goes on for five complete minutes about how much he loves everything about him and how a chubby tummy is supercute and comfy to lie on and nice and soft.
kyoutani replies by blushing heavily and wiping away a quick tear before telling yahaba he's a giant idiot and hugging him tightly.