Koji Yamase 山瀬功治 is a Japanese footballer who plays for Yokohama F. Marinos of the J-League. Japan's coach Ivica Osim handed
him his first senior cap on August 9, 2006, in a friendly match against Trinidad and Tobago. His first goal for Japan came
on August 22, 2007 in a friendly match against Cameroon. Yamase also played for Japan at the 2001 FIFA World Youth Championship
in Argentina. His younger brother Yukihiro is also an professional foootballer currently playing for J.