Ryuichi's former manager and now the manager for Bad Luck, K is aggressive in promoting the band--he even carries around a big gun and hand grenades. His concern is first and foremost Bad Luck, but in his shaping of the band's career, he ends up involving himself in Eiri and Shuichi's relationship. He is American, and in the original Japanese version, they played on the stereotype that Americans always have guns and will pull them out any time, any place. K often speaks English mixed in with his Japanese. K's real name is Claude K. Winchester. Also in the manga it is shown that K has a family; he has a wife named Judy Winchester, and a son named Michael Winchester.

Source: Wikipedia