Identify I do not remember the name of a manga hentai?

[nadie]

Someone knows of a manga hentai that includes Netorare, Sex toys, Ahegao, Blackmail and Anal.
The duration of the manga I think it's three chapters.
Is about a "teacher" blackmail a schoolgirl, makes her addicted to anal sex.
At the end of the manga he takes the virginity while the boyfriend sees how it happens.

 

[squilax]

Ntr² that's is the name.