Tatsuya was born the second son in a family of three brothers. His mother, Yumi, had the impression that he was a quiet and unassertive child, but... One spring, my older brother went to work and lived alone, while my younger brother enrolled in a boarding school on a sports recommendation. My father went away from home and his life changed abruptly, and mother and son began living together. Yumi felt a sense of loss as the bustling house suddenly became quiet. Seeing his mother like this, Tatsuya felt an indescribable jealousy, and tried to regain his mother's affection, which he had never been able to monopolize.