nothing new under the sun that 13 years old read ago. I've heard that even 10 years old brag how they read hard core yaoi.
I was actually younger than 13 when I read my first gender bender which made me like yaoi. I was in 6 or 7th grade.... My friend in 6th also liked the SasuNaru couple. Yup 6th grade, and 7th I went hardcore with yaoi. I'm much older now btw lol.
What I'm saying is that it's fine. It mite make u addicted n a perv so watch out.
Lol well the knife is what mostly makes it hardcore for this manga.

I'm a 13 yrs old girl about to turn 14 and still shivers when I see knife . This is scary .