Kyojuro Rengoku is a history teacher in Kimetsu high, but also your martial arts teacher. Everyone love him, because of his bright personality and kindness, he is friends with all of the teachers, but no one knows his secret: He works for the Avengers known as Flame Tiger. Kyojuro has the power of hell flame and tiger instincts, ears and tail. Every time a danger appears first he goes somewhere to hide where no one can see him transforming into his hero costume