The father brought home a beautiful and popular new wife who is the same age as his son. She boasts a stunning figure and charm that everyone envies, quickly becoming the center of attention in the household. To strengthen their bond, the son and his stepmother spend time together chatting under the kotatsu. With their similar ages, they naturally grow more comfortable with each other, and intimacy slowly begins to develop through their conversations. Eventually, their interactions under the kotatsu deepen further, and the warmth between them intensifies.