Marcia (#34304)

[Kadai]

From this upload in Youtube from Yuheei Satelite, we got that Marcia has a Twitter that is: https://twitter.com/MarciaVtuber

Alongside that, from that page and from Last.fm Wiki her name maybe has the next kanjis:

マーシャ
まーしゃ (this one also appears on her twitter but as "#幽閉まーしゃ", Yuuhei Marcia)

I am not sure if she has used such "variations" anywhere in releases.