Omocha Kaihatsubu Buchou wa Jibun de Kaihatsu Shita Omocha no Jikkentai kara Bai Gaeshi Sareru You desu

The head of the toy development department initially uses her assistant as a test subject for a new vibrator, but the assistant quickly turns the tables to exact her revenge. Dominating her boss, the assistant inserts a large, textured vibrator into the department head and increases the intensity to force intense orgasms while recording the reactions on her phone. The assistant then straddles the department head, smothering her face with her large breasts as the toy continues to operate. Eventually falling asleep on top of her boss, the assistant leaves the department head trapped and continuously stimulated throughout the entire night. Waking up the next morning, the assistant pulls the toy out of the exhausted, fluid-covered department head, praises her incredible stamina, and cheerfully vows to continue following her.