Koukou Tekken-den TOUGH (lit. High School Iron Fist TOUGH, English title TOUGH: High School Iron Fist Legend) is a 1994-2003 martial arts action manga series by Saruwatari Tetsuya. A sequel series, titled simply as TOUGH, was introduced in 2004-2012. A spin-off series, Oton, had been serialized in Business Jump in 2004. The third installment, Ryuu wo Tsugu Otoko, were published in Weekly Playboy Magazine since 2015.