First I thought the dads would end up together. Second so what does that make the boys now...

no they r not. they are still kinda cousins, just more distant, since its not the brothers child but the cousins child child. so great-cousins.

Ok, so when I say Shougo's father (Ikuomi), I mean the non-biological one. So according to the family tree, Kazumi is the son of Shougo's father's sister. Since Shougo is actually his father's cousin's (Masahiro) kid, that makes him and Kazumi second cousins. I hope that makes sense. And technically, Shougo's father is his first cousin once removed. But Shougo can also just be considered his father's nephew. Yeah family terminology is confusing.

Omg, but thank you :D I understand now a bit better ╥﹏╥

Kazumi is shougo's cousin. Kazumi's parents are not mentioned in the manga. Don't misunderstand. Kazumi is not the son of the shougo's biological father. They are just cousins.

I feel sad for shougo's father(one who raised him). He was betrayed by his wife and his own cousin who he treated like his younger brother. I don't blame for his strict behaviour towards shougo but we can't actually call that strict. Cause it's not like he hit or blame shougo or something it's just he doesn't knew how to show his love. And shogou's mother is a cheater. Good thing she died early. I won't feel sorry for people like that.