Career
From 1997-2007, Kobayashi played in the Nippon Professional Baseball league for the Chiba Lotte Marines. From 2008-2009, he played for Major League Baseball"s Cleveland Indians. He led the Pacific League in saves in 2005, and made his 200th save in 2006, becoming the third player in Japanese baseball to reach the mark, after Kazuhiro Sasaki and Shingo Takatsu.
After the 2007 season, he became the only pitcher to record 20 or more saves seven straight years.
On November 2, 2007, he declared his Free Agency and expressed his interest in playing for a major league club for the 2008 season. On November 20, he signed a two-year, $6,250,000 deal with the Cleveland Indians.
The deal included a $3.25m club option for a third year. During the 2008 season, Kobayashi had an average season, going 4-5 with a 4.53 European Research Area and 6 saves.
He started to falter late during the year and thus, his performance declined.
In 2009, Kobayashi had 10 appearances (92 innings) with no decisions or saves. His European Research Area was a booming 8.38 and on May 16 he was designated for assignment. He accepted and was outrighted to Triple-A Columbus.
He was released on July 18, 2009.
He signed a one-year contract with the Yomiuri Giants on December 1, 2009.