Zenitsu was trained by Jigoro Kuwajima, a former Thunder Hashira of the Demon Slayer Corps. While Zenitsu and Jigoro were fond of each other, Zenitsu was never able to master beyond the first Form of Thunder Breathing while under Kuwajima's training. Kuwajima's other student, Kagaku, did manage to master all of Kuwajima's Thunder Breathing techniques.