 By at least late 1990, he was directing adult videos for the HRC Cher label, including "The Female Teacher's Nightmare Trap 4".In November 1991, he directed Riria Yoshikawa's retirement video, "Making love with my husband (her retirement)", for HRC.In March 1991, Kaji formed his own adult video studio, Hot Entertainment, and, by 2000, he was "a veteran director of over 150 adult films and videos."