Tsuboi was educated at and played for Yokkaichi Chuo Kogyo High School andFukuoka University.
After graduating from the university in 2002, he joinedUrawa Red Diamonds and immediately broke into the first team. His first appearance came on 3 March 2002 againstYokohama F. Marinos in opening game in2002 season. He scored his first league goal on 17 May 2003 againstGamba Osaka. He won the Rookie of the Year award in 2002 and was selected as one of the J.League Best Eleven in 2003. In 2006, Reds won the champions inJ1 League which is first J1 champions in the club history. In 2007, Reds won first Asian titleAFC Champions League. Although he played many matches as regular center back until 2010, he could not play many matches from 2011.
Japan's national coachZico gave him the first cap in 2003 when he played Tsuboi on 11 June 2003 in a friendly againstParaguay atSaitama Stadium.[5] He was a member of the Japan team for2006 FIFA World Cup where he played 2 games againstAustralia andBrazil.[5] In Japan's first match against Australia, he suffered from cramps in his both thighs and had to be replaced byTeruyuki Moniwa in the 56th minute.
He was also in the squad for2007 Asian Cup but did not play any game in the tournament asYuki Abe andYuji Nakazawa were the first-choice centre backs.
On 8 February 2008, he announced retirement from international football.[6] He played 40 games for Japan until 2007.[5]
