Unlike all you yaoi fangirls seem to think, this has nothing to to do with Gen being gay. He's just too used to having a lackey who doesn't ask questions and whose life and circumstances he can utterly dominate as long as Reiji lives in town. It's simple cruelty.
Really hope the twist is that Gen have the big gay. But knowing the manga, he's just a obsessive control freak that loves having slaves and treating them like trash.
@bastek66 ppl are wondering about that because MC's mother told him she knew him, since they were schoolmates. She knows some stuff about him too, and she warns MC to stay away from him. But if he would be the father, MC would certantly recognize him.
there's a possibility that he left home when MC was really young/baby, but I've seen raws for chp 17 and there's a flashback from a young Gen visiting Reiji's home and MC's father is there (or atleast it seems him) and at that age it seems kinda weird you wouldn't recognise your own father like 10/7 years later.
Bruh is he a yandere-obsessed bully guy or just gay for MC ? anyways all of the characters here is crazy (idk lol they just have an edgy inner thoughts)
edit : nvm i think he's bi 🧐
@jazz9 Before Hatsukoi Zombie (which ended up getting pretty messed up once the focus moved away from the MC), this mangaka did a series called Himegoto which got pretty messed up.