Choukyou Shigan Zuma ~Musuko ni Oboreru Mein no Uzuki~

Yukari is a married woman and has a reputation for being a virtuous wife.
However, she has a secret. She becomes obsessed with a very strong sexual desire just before her monthly period. She releases it by masturbation but when she finds a "bondage" website, she could not resist writing a message on its forum.
"Please train me..."

[From DLsite English]