Tatsuya was born as 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 following an introduction to sports. My father went away from home and his life changed quickly, mother and son began to live together. Yumi felt disappointed when the bustling house suddenly became quiet. Seeing his mother like that, Tatsuya felt indescribably jealous, and tried to win back his mother's affection, something he had never been able to monopolize until now.