You sick fuck. Your like 30 minimum inside
No he isn't. He's a kid who has extra memories. If you are going to look at that kid, and tell me "he's an adult", then you're also telling me that - for example - a 40+ year old woman seducing him is no issue. Take a moment to mentally picture it... Is that
really your stance? Or did you just not think it through? No matter the "on the inside" nonsense you speak of, he's a kid at this point and time.
The thing about reincarnation as a setting, everyone gets reincarnated countless times, but they generally don't retain memories of their previous life. Still it happens, and everyone becomes a child all over again, no matter how many
millions of years they lived in previous lives. The difference here, MC just got to keep some memories. None the less. kids are kids.
Oh and what if it was the other way? What if - just all of a sudden - she also regained the memories of a past life? Does that make it okay for some old man to seduce her? According to your "logic" here, that would make her an adult, correct? So then it must be okay! Right? No. She's a kid, and extra memories won't change that.
Isn't it from
Death March to Another World (meh), where there is a little girl, 8 years old or so IIRC, who has her previous life's memories? She's trying to seduce the MC, arguing that she's really an adult. The MC rejects YOUR position, and doesn't screw her. Maybe she used to be an adult, but she's still a kid.