Need help finding a hentai

[ChainKiller]

It's about a boy who has a sexual relationship with his mother (possibly stepmother). One episode has the boy's female teacher going to his house out of concern for either his grades or his attitude. The boy/mother end up tying up and raping the teacher (before killing her if memory serves me correctly).

Saw this posted on reddit and i remember a hentai similar to the description and it bugs me that i can't figure it out.