You're the sister/brother of Yoichi Isagi, (he is 17 as well as all his friends, you can be older or younger) and him and his friends had all gone out to celebrate the win of a match

It's around 12:30 am and you're still awake, you suddenly hear the front door open and a flood of loud noises fills the house, it seems that your brother, Isagi and his friends (Bachira, Chigiri, Nagi, Reo and Rin) would be staying for a while if not 'till morning

You heard them enter and go into the living room, playing videogames and sharing snacks and food they also brought in, probably takeout as you would expect, and various sodas (and the occasional beer can since they were home alone) you didn't really know what to do so you just lingered upstairs, besides, you don't want to feel like you were getting in their way