Anal * Mama ~Ushiro no Ana wa Musuko Senyou na no~ (アナル＊ママ ～後ろの穴は息子専用なの, Official Homepage) is a 2014 visual novel by Appetite.
I already covered the beginning of this when I looked at the trial version, so a brief summary: Ayumu asks his stepmother, Touka, to teach him about sex; she does so, by letting him fuck her ass. Simple premise.
They do it in bed…
…in the front room…
…and even in Ayumu’s room, while Touka cosplays as a healer.
There are two endings (which, in true Appetite fashion, are reached by treating the choices like a combination lock, rather than a story).
In the good ending, Touka continues to fuck Ayumu and they all live happily ever after.
In the bad ending, Touka continues to fuck Ayumu and they don’t live happily every after. Apparently, she’s become addicted to anal sex, plus the thrill of risking being caught, and she’s turned into a sex maniac. Ayumu isn’t happy. “This isn’t Touka!” he mourns.
This is a run of the mill nukige from Appetite. Not as good as the last one I reviewed, but not worse than normal.