The story follows a 34-year-old man who is killed after trying to save someone from getting hit by a car. He soon finds himself reincarnated in a magical world as Rudeus Greyrat, except that he gets his whole life reset, starting as a baby.With all of his knowledge from his previous life, and a new heaping helping of magical ability, Rudeus quickly becomes a formidable warrior ready for adventure. Oh, and he's still a total pervert.

JD (Junk Dog) participates in fixed boxing matches in an underground ring in order to live. Today, he enters the ring again, but he encounters a certain person. JD wants to take on a challenge that risks everything.

"Healing magicians cannot fight alone." Keyaru, who was bound by this common knowledge, was exploited again and again by others. But one day, he noticed what lay beyond healing magic, and was convinced that a healing magician was the strongest class. However, by the time he realized that potential, he was deprived of everything. Thus, he used healing magic on the world itself to go back four years, deciding to redo everything. This is a heroic tale of one healing magician who became the strongest by using knowledge from his past life and healing magic.

Long ago, a war broke out in Japan that pitted Kantou against Kansai and divided the country. Kansai became dependent on Kantou, but slowly the police and government began losing control of Kansai to criminals known as Akudama.