As a 21-year-old, Takeuchi averaged 6.2 points and 5.2 rebounds per game for the host Japanese at the 2006 FIBA World Championship.[3] Takeuchi has earned a bigger role with the Japanese team over the past four years; his best tournament performance to date was at the FIBA Asia Championship 2009, in which he averaged 9.8 points and 7.2 rebounds per game.[4] Despite his performance, Japan stumbled to a disappointing tenth-place finish, its worst ever performance in 24 FIBA Asia Championship appearances.
Takeuchi played professionally with the Hitachi SunRockers of the JBL Super League. In the 2009–10 season, Takeuchi entered the month-long winter break averaging 16.1 points and 9.4 rebounds per game for the third-place Seahorses.[5] He was also named to the JBL All-Star Game as the leading power forward vote-getter for the East.[6]