During the summer break of the high school, a mysterious vessel used for the ritual was sent to the archaeology club. The club members and I lost our conscience when the light from the vessel illuminated us. When I came to, my conscience was transferred into the body of Kurahashi Yoshimi whom I adored like my elder sister. Her body of a girl was very soft, smelled good, and so sensitive to sexual pleasure. It was unfair that the woman was totally different from the man... The other members exposed to the light from the vessel exchanged their minds and bodies, and they were taken into the secret world of the sexual desire. The strange phenomena repeated over and over. Would they be able to return to their world?