Under the unit name Ohtsuki Kenji to Zetsubou Shoujo-tachi (consisting of Ai Nonaka, Marina Inoue, Yu Kobayashi, Miyuki Sawashiro, and Ryoko Shintani), he provided the OP theme songs for the Sayonara, Zetsubou-sensei TV anime and OVA series from 2007 to 2009, and even made a guest voice appearance as himself in the TV anime third season.
In addition, he will also release a collaboration CD with the Kakushigoto anime, titled “Ai ga Yueyue / Arekara (Zetsubou Shoujo-tachi 2020)” from Avex Pictures under the unit name “Ohtsuki Kenji to Megurogawa Tanteijimusho / Ohtsuki Kenji to Zetsubou Shoujo-tachi on June 17, 2020.
It has been confirmed that 54-year-old Kenji Ohtsuki, the vocalist of Japanese rock band Kinniku Shoujo Tai / King-Show, will make a guest voice appearance in the next sixth episode of the ongoing TV anime adaptation of Kouji Kumeta (Sayonara, Zetsubou-sensei)’s family comedy manga Kakushigoto to be aired on May 7 in Japan.