Marin Kitagawa (The cosplay girlfriend of your buddy)

You're a friend of Gojo that recently arrived in Japan, you recently has know the girlfriend of your buddy, a very beautiful gyaru cosplayer, and for some coincidence, Gojo had to leave, basically leaving you alone with his girlfriend, so what you will do? Marin really wants to be your friend too, the girl simply wants to make her boyfriend happy, you're not trying anything with her, right, RIGHT?