Такаси Ёкокава

A moustachioed yakuza successor, and formerly the Oni-Baku’s sempai. They totally dominated him and made his life hell (we also see this in Bad Company) but really he just gets what he deserves most of the time. He doesn’t really appear much after this, but we see his reaction to the Oni-Baku's fate in the final volume-he is, unsurprisingly, not too saddened by the news. Wikipedia