Based on the erotic game by POISON.

He has been treated like a servant by his older childhood friends, sisters Hina and Serina, but worst of all, Hina ends up tutoring him for his entrance exam. One day, however, the owner of a secret club comes in and gives him a hypnotic product. He immediately uses it on Serina, his sister's servant, to "make her understand" his intentions, and begins his lewd revenge by cuckolding her and enslaving both sisters as sex slaves!!

(Source: Parabook, translated)