A female employee, Natsu Igarashi, who has been trained to have a sensitive body that can cum instantly after being harassed by her boss, whom she hates.

Natsu, who is plain and inconspicuous, has a weak personality and cannot refuse. One day, she is confessed to by Sato, who works in the same department, and they start dating. She usually wears plain glasses and has messy hair, but the manager notices Natsu's interest in her and starts to sexually harass her the next day... Natsu, who cannot refuse, gradually develops breasts and is trained to have an instant orgasm, and falls into pleasure...