This is scum. I don't care what kind of background story the author gives to us about him. He will still be pure utter scum. To walk out on a wife after having had 3 children with her ... with her still pregnant with the 3rd, absolutely despicable. Then to go out, find someone else, start a family as if nothing is wrong. Seeing that he's never seen Momo, I barter that he didn't even come to the mother's funeral. Absolute piece of shit. His reasoning for wanting to suddenly be "family" all of a sudden, right when Oji-san is sick and in the hospital, is sus as fuck. He's fucking scheming something. He acts as if Kiriyama is the one butting in, when honestly Kiriyama has probably done much more than he's ever tried to do since he left. He has no right to act as if he's family at this point. Just because you have blood relations doesn't automatically make you their dad. In the words of Yondu from the film, "he may have been your father boy, but he wasn't your daddy."