nazono mito
A version of Tsukino Mito that debuted with her 2019 April Fools stream. Later nicknamed Nazono Mito (謎ノ美兎 lit. Mysterious Rabbit) by fans, the mysterious figure appeared in full Tsukino Mito cosplay (including a kigurumi mask and zentai bodysuit).
The stream and the bizarre character were very popular among fans, and perhaps because of that, Nazono Mito later appeared in Tsukino Mito's TV commercial on December 31st. She made a reappearance on Mito's 2020 April Fools stream, with two minutes of cut content being released days later.