Tatsuya was born the second son of three brothers. From her mother, Yumi, I had the impression that she was a quiet child who did not assert herself. In the spring of one year, my older brother got a job and lived alone, and my younger brother enrolled in a boarding school on the recommendation of sports. The father was assigned to work alone, and his life changed in a hurry, and he began to live with two mothers and children. Yumi's bustling house suddenly becomes quiet, and she feels a sense of loss. Seeing such a mother, Tatsuya felt unspeakable jealousy and tried to regain his mother's affection, which he could not monopolize until now.