The "God of Death" on the battlefield returns to his middle school days. Kuroda Masamune, a mercenary who single-handedly turned the tide of battle on the battlefields of East Africa, faithfully obeyed his father's teaching, "Don't have a will, follow instructions," and lived as the ultimate "tool," but he loses his life due to betrayal during a mission. However, when he opens his eyes, he is supposed to be dead, and it is 15 years