Its mixed martial arts because Kenichi trains in multiple disciplines and utilizes the techniques of multiple styles together in corabat. Later in the series, he develops a "signature move" of sorts that essentially corabines muay thai, karate, and kung fu.
Also, Funimation announced at AX that they will be doing the second season! YAY!
Now all we need is for Capcom to release the video game over here and for someone to pick up the manga license. We need the excellent manga over herer as well.