Six months ago, his father moved away from his father and his stepmother (Akari) seemed lonely. As if to ease her loneliness, her stepmother was sweating while doing housework... Her son (Yuichi) was worried about her, but one day he accidentally witnessed her having phone sex with a man other than his father! Yuichi was more excited than angry by his stepmother's lewd appearance and seductive voice, and he could no longer suppress his lust in front of his stepmother's sweaty body...