After being hit by a truck and dying, a homeless and jobless Japanese man reincarnates into a fantasy-like world as Rudeus, son of the swordsman Paul Greyrat and his wife, the healer Zenith. Keeping his memories of his previous life, Rudeus quickly learns to read and eventually starts practicing magic. Noticing his aptitude, Rudeus' parents hire the adventurer Roxy Migurdia as his magic teacher. Roxy has some doubts at first about tutoring him due to his tender age until she witnesses his unique ability to cast magic instantly and realizes his potential...