Yuina, a girl in love with her non-biological brother, lives tormented by her lack of self-confidence. One day, a mysterious voice guides her to an unknown world. Without understanding what is happening, she is attacked by a man. In that desperate moment, she is saved by the specter of a succubus possessing her body. The succubus defeats all her enemies by fucking them, not caring what happens to Yuina's body and mind.