Boku ni Sefure ga Dekita Riyuu

Two part-time employees from the same coffee shop, Saki and Koharu, are schoolgirls. Saki is an aggressive blonde, while Koharu is a timid girl with a bob haircut and large breasts. They visit the room of their male coworkers to socialize. Saki, driven by curiosity about the male body, seduces one of the young men. She proceeds to have intercourse with him in Koharu's presence. This incident establishes an unusual dynamic. From that day forward, the timid Koharu, unable to voice her own desires, repeatedly observes the couple's sexual activities.