Yui goes undercover as a semen investigator. Her current target is uncovering the secret behind "semen collection" operations taking place at a hospital. Infiltrating as a nurse, she receives cumshot after cumshot while performing blowjobs, swallowing semen with deep throating. Later, she goes undercover as a doctor to expose a conspiracy involving semen trafficking, enduring intense deep throating, ball gags, and erotic training that sends her into repeated orgasms. The video captures Yui's climax-filled body completely soaked in semen.