Although not related by blood, Miyuki and Ieda are siblings. Miyuki secretly craves her brother and doesn't want any other girl to have him. Ieda is hot for a girl named Noriko. One day, Miyuki catches Noriko kissing Akiyama. Miyuki fights with Noriko to stop this little affair.
At school, Noriko is now known as the town slut who loves to be mixed up in menage a trois. Lucky for her, Ieda and Akiyama back her up as being a good girl and they are all just friends who enjoy spending time together.
Will Miyuki come to accept the fact that her brother will only ever be a figment of her fantasies'
