Waka is a modest and demure female college student with a 100cm bust. Her younger sister, Satori, secretly has a crush on her best friend, Hikaru. One night, Hikaru is holding a study group, and while Satori is sleeping, she squeezes Waka's huge tits and makes her cum with cunnilingus and fingering. Hikaru is happy to be one with Waka, the woman she has feelings for, but Satori is suspicious of her sister and confronts her. Not knowing that they are in a love triangle, Hikaru aggressively pursues Waka's body, but...