After dying on Earth, Light Creston awakens in a strange cottage, believing he’s reached the afterlife. Instead, he discovers he’s now the living incarnation of a legendary weapon, The Holy Armament Excalibur.

His new “owner” is Dr. Constance Luna, an overpowered and short-tempered sorcery genius who only acquired the Excalibur based on a legend she was told: The man sealed inside could grant her one wish.

But after unsealing the weapon and finding Light—confused, clueless, and utterly useless for her purposes—she decides to get her money’s worth by making him her full-time assistant.

All is not as it seems, however. As Light endures increasingly bizarre tasks from his new master, he discovers strange abilities emerging within him. Each discovery raises more questions about the weapon he spawned from, its former wielder, and a mysterious conflict threatening this new world.

But first, he needs to survive Constance's to-do list.