Chris, the third son of the Ford family, grows up deemed useless despite high expectations. Mocked with the nickname Useless, he is disinherited at the tender age of twelve. Driven away, Chris discovers a strange grimoire in the library that allows him to adjust parameters and modify various forms of magic.

Having always possessed a passion for magic, an excited Chris begins altering spells and casting them one after another. As he leads a carefree life creating original magic, difficult challenges cross his path continuously. Unaware of the true scale of his power, Chris somehow resolves every crisis effortlessly without even realizing it.