After her parents passed away, schoolgirl Natsuki continued living alone, struggling to get by. Her uncle's family, consisting of only men, repeatedly urged her to move in with them, but she refused out of fear—they always stared at her big tits with lewd eyes. However, the relatives living in the same apartment building began targeting her, threatening her daily and forcing her into increasingly degrading sexual acts, pushing Natsuki further into despair.