Kotobuki Tsukasa was born April 28, 1970 in Tokyo, Japan. He is a character and mecha designer and illustrator. His line of work includes many anime but also video games, such as Saber Marionette J, Knights of Ramune, Cyber Team in Akihabara and Battle Arena Toshinden. He also did the art for Sword of the Dark Ones.

He works often together with Oobari Masami on shows and was referred by him as the character designer of Toshinden to Sony, because Oobari was busy with different things at that time.

Kotobuki started as illustrator already during high school, using the pen name Sushi (寿司).