Shinkawa Hiromu

The boy who sits behind Tomohiro in class.
He's strangely proactive about interacting with our protagonist.
That cute face is androgynous, and in fact some would say it's girly.
You might even find yourself flustered with that small build and somewhat bright voice.

Translated from the official website

He's the face behind the popular VTuber Rema-chan (レマちゃん), who consistently gets over 100,000 views on her daily morning horoscopes. In addition, he's a famous crossplayer known as Mare-san (稀礼さん).