Makito Shindo, son of a powerful hospital director, dreamed of saving lives. But after his father’s sudden death, he discovers that he had many enemies simply because of his lineage. Betrayed by a fellow doctor, ruined professionally and financially, and forced into hiding, Makito’s life ends in a tragedy... until a mysterious “Game Over” message gives him a second chance. Now, armed with a mysterious power and the resolve to reclaim what he’s lost, Makito embarks on a journey of revenge and salvation, determined to protect the lives he couldn’t save before. (Source: WEBTOON)

The "Grim Reaper" of the battlefield returns to his middle school days. Kurona Masamune, a mercenary who single-handedly turns the tide of battle on the East African battlefield, faithfully followed his father's teachings: "Don't have your own will, just follow orders." Living as the ultimate "tool," he loses his life due to betrayal during a mission. However, when he awakens, he finds himself in a middle school classroom 15 years in the past. "If I could do it over, I could do it better..." With this dying regret in his heart, the strongest former mercenary crushes evil within the school with "his own will" in this revenge action! Source: [eBookJapan](https://ebookjapan.yahoo.co.jp/books/986099/?type=serialStory), Translated