Keiichi, a man remarried to Reiko, now has two stepchildren. However, Reiko's voluptuous and seductive figure becomes a powerful stimulus for his adolescent sons, Kenji and Masao. With Keiichi constantly working night shifts, his marriage falls into a sexless state. Witnessing this, the two brothers begin to desire Reiko as their own. Masao innocently exposes his erection, seeking sexual release, while Kenji, pretending not to notice at first, later whispers, "Do it to me too." The brothers' desires grow increasingly twisted, intensifying their longing and driving Reiko into deeper emotional and physical entanglement as their forbidden relationship escalates.