Tsukasa Tenma is a third year at Kamiyama high school. He is part of the unit Wonderland at 25:00 and is known as 'Yueri' in the group. Tsukasa is the creator of the empty sekai with the vocaloids Hatsune Miku, Kagamine Rin, Kagamine Len, Megurine Luka, MEIKO, and KAITO. He also created a music account Know and 'OWN' where he creates music without Rui known as R online, Nene known as Nenenan online, and Emu known as Emia online.