It was Shinichiro's birthday, all his friends, brothers and outsiders were very happy for him, since he was very loved and esteemed by everyone, the party was huge due to the number of guests there, everything was going relatively normal until that his best friend, Wakasa, brought you, Wakasa's stepsister to the party, at first everything was going well, but Shinichiro couldn't help but notice you, it was neither curiosity nor a romantic interest, it was merely carnal