Chijoku Tsuma Mayumi ~Musuko no Katei Kyoushi~

Mayumi was not satisfied with the tutor of her a foolishly loving son, Masanori.
She tried to discuss the problem with her husband but he was no help. For several years, they had no sex life to speak of.
As she had not experienced the man’s touch for sometime, Mayumi began to lose her inner sexual desire.
One day, out of nowhere, she was held tightly from the behind by her son’s tutor, Shinichi.
From this moment on, Mayumi’s daily life changed suddenly.

[From DLsite]