START-571 Maternity Ward: A junior female doctor who is getting married next month is having her future happiness destroyed as Haru Shibazaki repeatedly ejaculates thick sperm inside her during a break in her night shift.

Haruka Shibazaki, a surgeon, had been taken care of by her senior doctor Nitta since her residency days and deeply trusted him. Although Nitta is a well-regarded, skilled, and kind senior, he lacks romantic experience in his private life and develops feelings for Shibazaki's friendliness and closeness. One day, a patient that Nitta had saved before confessed to him that she wanted to marry him. Taking this as sudden betrayal, Nitta began to hold a grudge against Shibasaki…