Tae-seong, a mixed martial arts professional with excellent skills, is injured and got disqualified as he gets caught up in a fight with his friend Byeong-jin inside a store ahead of his UFC debut. Hye-na, Byeong-jin's younger sister and BJ professional in mixed martial arts, encourages Tae-seong to make a comeback, but Tae-seong refuses.  Hye-na finds out that the man who injured Tae-seong is Yang Ho-yeol, the strongest champion of "Blood Street", an illegal gambling game site where one can bet after a real street fighting match, and she informs Tae-seong about it. Tae-seong jumps into "Blood Street" for revenge. "Blood Street" users go wild, calling masked Tae-seong a "real fighter".  Tae-seong and Ho-yeol break "Blood Street" and start a fight to be the real champion!