At some point, Daisuke and Ken started cuddling each other for comfort each time they would hang out. This could be to help Ken deal with his troubled past, for them to feel closer to each other as if they were Jogressing, or just because they like being touchy-feely with one another. They try it once and then it just keeps happening: every time they hang out, they will end up holding each other and snuggling together, often falling asleep. It gets to the point where it's the number one thing they look forward to doing together. Where you take that is up to you: maybe this helps them realize their feelings for each other, maybe it leads to confusing hormone-addled exploration. Does not need to be smut, but could lead to that if you like.
Age: middle school-high school.