Matsui began his professional baseball career in Japan, playing in the Pacific League for the Seibu Lions starting in 1995. He continued there until 2003, playing shortstop and leading the league in stolen bases. With the Seibu Lions, he won the Pacific League Championship four times, and in 1998 was selected as the league MVP.

On December 10, 2003 Matsui signed as a free agent with the New York Mets where he immediately joined the roster for the 2004 season. He played shortstop with the Mets for his first season, but was moved to second base in 2005 after several errors in 2004.

Matsui was traded mid-way though the 2006 season to the Colorado Rockies on June 9, 2006. He finished the season with the Rockies, hitting 22 runs in 113 attempts at bat and stealing eight bases. He re-signed with the Rockies following the 2006 season, and appeared in his first post season game the following year. Matsui joined the Rockies in the 2007 World Series, where they lost to the Boston Red Sox. Following the loss, he was granted free agency.

On December 1, 2007 Matsui signed as a free agent with the Houston Astros to a reported three-year, $16.5-million contract.

1. Full name: Matsui Kazuo
2. Born: October, 23, 1975
3. Birth Place: Osaka, Japan
4. Started Career at Shortstop, but moved to Second Base in MLB
5. Nick Name: "Kaz"