The unit Zetsubou Shoujo-tachi was formed by the latter’s five main voice actresses: Ai Nonaka (Kafuka Fu’ura), Marina Inoue (Chiri Kitsu), Yu Kobayashi (Kaere Kimura), Miyuki Sawashiro (Taro Maria Sekiutsu), and Ryoko Shintani (Nami Hitou), to perform its OP theme songs collaborated with Kenji Ohtsuki, the vocalist of Japanese rock band Kinniku Shoujo Tai / King-Show.
The unit consists of the four main voice actresses from the Kakushigoto anime: Rie Takahashi (Hime Goto), Ari Ozawa (Silvia Kobu), Kaede Hondo (Hina Toumi), and Azumi Waki (Riko Kicchi).
In a two-minute preview video for the upcoming collaboration CD with the Kakushigoto anime, the five-original members of the unit Zetsubou Shoujo-tachi from the Sayonara, Zetsubou-Sensei anime are confirmed to return to perform a new song “Arekara” (Since then) under the unit name Zetsubou Shoujo-tachi 2020.