After school, Ai, a high school girl, is taken to a certain room by her best friend. A middle-aged man is waiting for her in the room, and her best friend straddles the man's lap and begins kissing him without hesitation, surprising Ai with his bold behavior. Her best friend shows off their affectionate behavior and invites her to "kiss together♪", but Ai refuses, saying "No way", but she is excited by the strange situation of seeing the two of them kissing passionately, and her crotch gets wet... A kissing affair between a high school girl and her best friend, whose body is developed by a middle-aged man she has never met before.