The demon-infested dimension called "Mato" poses a threat to humanity. There's a special type of peach tree in Mato whose fruit grants special powers, but only to women. As a result, women gain higher social status as protectors of humanity, while men become second-class citizens struggling for recognition. Enter Yuuki Wakura, a resourceful high school senior whose sister vanished during a Mato incident five years ago. While grappling with the challenges ahead, Yuuki finds himself trapped in Mato during an event. He's swiftly rescued from demons by Captain Kyouka Uzen of the Anti-Demon Corps, who bestows upon him powers as her "slave," transforming him into a formidable beast mount that fights demons.
However, there's an unexpected cost to being her "slave"... and it's not Yuuki who has to pay it.