After losing his little sister to an incurable disease, world-renowned medical researcher Kanji Yakutani dedicated his life to inventing new medicines in order to cure patients. The former pharmacist wakes up as a 10-year-old child whose body has been struck by lightning after working himself to death at the age of 31. He discovers that he has been reincarnated as Falma, a child of the respected De Médicis family, in a medieval world. Falma realizes that his body is host to the guardian deity of medicine in a world where divine arts—magic granted through blessings from guardian deities—exist. The boy has been endowed with the mythical divine arts of creation and reduction, as well as the ability to diagnose illnesses in people's bodies instantly.