Leo Hyakujuu

Leo is a new student who transferred to Katta Kirifuda's school. He constantly repeats the phrase "Ore wa Leo" ("I am Leo"), which is referenced in the card-name of Codename Orewaleo.
He was a big fan of Duel Masters and YA.RA.SI band, but he also wanted fame. So one day he got on the stage of YA.RA.SI's concert in order to get the attention of the world. At that same time Osamurai Van Osamu asked him who is he, he replied that he is a duelist. Osamurai showed him Coro Coro magazine with Katta on it as a new champion in the world of Duel Masters, Leo replied that he also want fame in Duel Masters as well.

(Source: Duel Masters Wiki)