I guess he just wants to vent.
Hisaki and Yasha are an odd pair of friends: Hisaki is quiet, distant, and possibly keeping secrets from everyone, while Yasha is loud, violent, and in serious need of anger management. As they try to deal with each other, they soon find that creatures are after them for something they know nothing about: a demon supposedly hiding within one of them.
I dunno… Kakon got tortured. Pretty sure his baggage is worse than yours.
Yes, call him names. That will help things.