Tooru frequently stays over at his older brother's house, gradually becoming entangled in a secretive relationship with his sister-in-law. She is a stunning, sensual woman, and the time he spends with her in everyday life becomes increasingly intriguing. Tooru begins secretly watching her—bathing, changing clothes, moments with his brother—discovering hidden allure in these ordinary routines. Yet, his actions haven't gone unnoticed by the married couple. From the cracks of daily life emerges a strange, complex relationship, concealing truths waiting to be uncovered.