I remember more less that is a guy (same at least I think) that start to became private teacher of a younger guy...
But the true is that the younger is his step bro... And him(the older) want to take revenge bc of his mother suicide (when he was younger).
Thank you in advance (づ ̄ ³ ̄)づ
http://www.mangago.me/read-manga/lock_you_up/
is it this one ?
But I think maybe is a subliminal message about not having to rush the feeling of being "grown"...
Just bc everyone is doing it... And is ok to be strange as a teen?!