In order to stop the invasion of the demons and seal the evil god that has been resurrected after a thousand years, Grey embarks on a journey together with his sister, Fiona, and his comrades. At the end of their journey, they were facing the evil god, and all of his comrades, including his little sister, were killed because of the evil god. Being the only survivor of the journey, Grey was hailed as a hero and was granted the throne as the emperor of the holy empire, gaining glory and authority. Unfortunately, Grey couldn’t recover from the grief of losing his one and only sister and decided to use any means necessary to revive her. After countless attempts to try and revive his sister, Grey became hopeless, until he heard a mysterious voice saying: *Do you want to save the most precious person in your life? If you’re willing to sacrifice everything, I will show you the way.* After making a deal with the mysterious voice, Grey found himself standing in his hometown that was supposed to be destroyed by the invasion of the demons.

In modern-day Shibuya, ninjas still exist. One of them is Enma, a master of fire techniques and the second son of the Iga Six Brothers. The brothers covertly protect the city by accepting requests for helping people and conducting spy missions. However, following the shocking event where the eldest brother, Shido, murders their father, Enma and his siblings become entangled in a series of incidents and battles against rival Koga ninjas. The central question remains: Can Enma reunite his family and continue safeguarding the streets of Shibuya? [Original Webtoon](https://jp.piccoma.com/web/product/179667)

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