Backed by a dawn-lit sky, a serene residential neighborhood hosts a stately Japanese-style mansion. Inside, exuding the elegance of upper-class society, a woman in an apron prepares coffee. She is Reiko, the beautiful and alluring sister-in-law, born from her husband's successful business run by her brother-in-law. Minoru, her brother-in-law's younger brother, dreams of becoming an artist but constantly faces harsh lectures from his elder brother. On this morning, after the elder brother leaves, the two return home with Reiko. A new event enters Minoru's daily life. Forbidden emotions begin to stir, and every intense moment draws viewers into the unfolding relationship between them.