Buddy He's sleeping with tons of girls cus he couldn't come out of the closet and the day he had a boner was the day he got a closet
So, as a child there’s a lot happening, physiologically speaking. It’s pretty common for children to see sex or aspects of it and feel something. It wasn’t necessarily him finding out he’s gay, but moreso that it’s a bodily function. Up to a certain age, children will start producing sperm and feel things bc it’s natural, but they don’t have deeper meanings.
It’s likely that he had that experience bc his body was connecting sexual tension with his own pubescent sexual organs.
Later on though, the act of his father cheating with another man and seeing his mom distraught turned into a “I can’t be him” to which he didn’t give into his same-sex desires, rather he lashed out by having multiple female sex partners.
I think there’s actually a lot more background context on how children are affected sexually that play into this really well. It might not be what you want to see, valid, but it’s an experience that is unfortunately very common.
Also it is stated that he saw a psychiatrist, but that can only do so much when you’re suppressing parts of yourself.
I just wanted to share some insight!
I don’t get the hype about this manga, the story is bland and disgusting, getting a boner as a child from seeing your father getting railed to sleeping with different women every second you get then all of a sudden falling for an innocent dude who’s the total opposite of you because you want to ‘ravish’ him? the mc should’ve just sent him to a therapist