Kairaku no Hatenai Kusari

The hardcore sexploit training of a futanari maid to her mistress.

From her earliest years, beautiful Marina had a yearning for her mother's maid, Rena. One day Rena suddenly became Marina's personal maid, and Marina was overjoyed.
Intimate at last, Rena revealed the truth beneath her skirt.
What followed was a lustful assault of pleasure upon Marina...

[From DLsite English]