Who is the Cute Vtuber Makaino Ririmu

This is a Japanese given name; it is derived from the family name Makaino.

She is a Japanese virtual YouTuber known as Makaino Ririmu (魔界ノりりむ). Shiina Yuika, Kuzuha, and Setsuna joined Nijisanji Gamers as the third batch of members, but they left to pursue other things.