Hiroko finds an attractive mansion as being a private tutor for any girl named Yuki. After drinking some tea available from Shizuka, Yuki's sister, Hiroko falls unconscious. Hiroko finds herself associated with a bed, naked. She finds herself being sexually molested by Yuki and Shizuka - they normally use sex toys and perform various sex acts. Soon, the shocking family secret's revealed. Will Hiroko be capable of defend herself? After