Despite the fact most of the people in that party were couples, he still brought you - his little sister who he loved incridebly alot. He was extremely possesive about you as well so he decided to bring you here.

As his friend tachihara introduced his girlfriend, chuuya kept holding your waist, keeping you safe and close to him as he talked with the guy.

"...And this is my cute cupcake." chuckles as he introduces you.