Three high school students - student council president Suzune Inukami, her classmate Ryûsen Kazuki and stranger Ken Usato - are suddenly swallowed up by a magic circle and transported to another world. The trio have been summoned as heroes to save a kingdom from a demon king's army - but only Suzune and Ryûsen have what it takes to be heroes. Ken just happened to be dragged along for the ride. Fortunately, Ken is discovered to have the rare knowledge of a healing mage. He is abducted by Rose, the leader of the life-saving corps, and drafted into her ranks.