In Tokyo, Rumina and Ginnosuke discover the Underground world of Elemental Users. Meeting Chelsea and Ruri, they embark on an adventure controlling Fire, Water, and other elements.

Under the capital city of Tokyo, Japan, there exists a large, vast, and unknown world known as Underground. There, people known as Elemental Users exist; people who have the ability to control the elements: Fire, Water, Lightning, Magnetism, Freeze, etc. Meet Rumina Asagi and his best friend Ginnosuke Isuzu, two average high school freshmen who reside in Tokyo. When they meet Gravity User, Chelsea Rorec, and the Maiden of Life, Ruri Sarasa, their whole lives change into one big adventure.