He’s the main rapist. The one who started it, that why he recognized the “fruit of his work” so quickly. I’m sure a sick fuck like him is pretty happy that not only did he cause Naoto great trauma, he also managed to leave behind a reminder of it. The only thing that I can thank him for is his one sperm that managed to make Shizumu-Chan. She was probably the only decent that can come from a dirtbag like him. Also I’m glad she looks like Naoto, because that rapist looks as ugly as his soul
Your serious comment about the manga itself ruined my stupid joke about how stupid manga logic is.
Imagine if paternity tests were like that in real life. Just look at the hair colour and touch it. If the same as male, must be dad now take responsibility.