Leon Sykes

Leon Sykes is a world-famous record producer from The United States, as well as a prominent figure in the criminal underground of the music industry. He is the primary antagonist in the manga and anime series.

He encounters Ryusuke Minami several times, usually in order to further his own personal gains and to tie up loose ends; whether it's involving a priceless guitar which Ryusuke had stolen long ago, or a potentially industry-shaking demo tape in Ryusuke's possession. Both have become quite wary of the other, with Ryusuke noting Leon's dangerousness, and Leon detesting Ryusuke's treachery.

Later on in the story, he develops a fixation on Yukio "Koyuki" Tanaka, after noticing his remarkable vocal talent and stage presence.

(Source: BECK - Mongolian Chop Squad Wiki)