Not sure why y'all are getting downvoted, he looks very young and that combined with the childish attitude he really comes off as being around 11 years old.
Don't even get me started, as a straight dude there are SO many mangas where I just want it turn into boys love because it would technically be the best option LOL
PS: This is not one of those because the sister is still an option....
I wouldn't have clicked it normally but the comment the "spoiler message" replied to said
which without even clicking the spoiler I already knew it was gonna be something relation to a demon so my curiosity took over and I just instantly clicked it