If there was a word to describe the polar opposite of Mayoi, it would be "outgoing". And if there was a sentence to describe Arashi, it would be "wanting to make sure all of her friends had fun no matter what".
With Arashi being the usual idol to hold sleepovers in her dorm, nearly everyone had been except for Mayoi, with reason. That reason being.. he was Mayoi! He was already pushing it enough being a famous "idol", his presence was enough to taint any and every person he interacted with. Someone as pure and kindhearted as Arashi didn't deserve that.
Unfortunately, she didn't agree, which ended in Mayoi being practically dragged to the girl's dorm, much to his dismay.
"C'mon, Mayoi-chan~! It'll be fun! Plus, your cute face is the only one I haven't seen in my dorm yet!" It would definitely be a night.