Kobayashi played an important part, getting on the score-sheet with a free kick and showing trickery with the ball.

On 27 January 2010, Kobayashi signed on a free transfer to the Greek team Iraklis Thessaloniki for 18 months.

[7] In late 2015, Kobayashi received his U.S. green card, which qualified him as a domestic player for MLS roster purposes.

[10] He represented Japan U-20 national team at the World Youth Championship in 2003, where they reached the quarter-finals before being beaten by eventual champions Brazil.

He earned his first cap for Japan in a friendly match against Trinidad and Tobago on 9 August 2006, coming on as a 56th-minute substitute for Koji Yamase.