Koo Kojima decided to become a cartoonist at age 15. At the start of his career, Kojima produced many cartoons, panels and etchings. His name became famous when he created adult comic strips like 'Sennin Buraku', 'Miss Doron Ototo' and 'Kuroneko Don'. More adult comic strips followed. Kojima has also drawn many cartoons, magazine and book illustrations and covers.