Ryuichi Kosugi is a Japanese comedian who performs tsukkomi in the comedy duo Black Mayonnaise. His standing position is on the left. His partner is Takashi Yoshida. Kosugi is represented with Yoshimoto Kogyo. He graduated from Kyoto Prefectural Katsura High School. In 12 November 2010 Kosugi married a former dental assistant from Osaka Prefecture.