I feel like he cried because he just saw what's a family for the first time and got the sadness of why he didn't had that.that panel of Ichi shedding a tear got me good, love the balance between him being a Dedicated Hunter and him learning to like, be a Person as more and more people end up in his life
Insane karma, he's going to be used by the person who captured him to take down World HaterBakugami in a karmic like justice ended up feeling despair.