One day, a large hole opened up in the yard of a house. There was a mysterious slime with a metallic body that was trembling and shaking. For some reason, Yuma Mitaka, a dull high school student, spends his days exterminating the "metallic slime" that springs up in the hole every morning. As he repeats this daily routine, Yuma's body undergoes an astonishing evolution! This is an unprecedented Musou fantasy that begins with an ordinary day!

One day, a large hole suddenly opened in the garden of the house. There was a mysterious slime with a metallic body trembling. Yuuma Mitaka, a dull high school student, spends his days exterminating the "metal slime" that springs up in the hole every morning. As he repeats this daily routine, Yuuma's body undergoes an astonishing evolution! "But this ability... is a bad thing if anyone finds out about it..." His ability is a secret, because it looks like a "monster" when it activates. It's only a matter of time before Yuuma's existence, which is too peculiar, shakes the world...!? An unprecedented Musou fantasy that begins with everyday life! (Source: Fantasia Bunko, translated)