Amateur career As a pitcher for Toko Gakuen High School, he won a 7–0 victory against Imabari-Nishi high school where he racked up 22 strikeouts. Later on, he struck out 19 batters at
Koshien Stadium and won a 7–5 game over Joso Gakuin. He also struck out the same amount in 2005, which ranked him along with Yoshinori Toda in 1963.
Tohoku Rakuten Golden Eagles In October 2013, five
Nippon Professional Baseball (NPB) teams selected Matsui in the
2013 NPB draft. The
Tohoku Rakuten Golden Eagles winning the rights to negotiate with him. Matsui signed with the Golden Eagles and made his NPB debut on April 2, 2014; his team scored 7–1 against
Orix Buffaloes even though he made only three runs. On October 11, 2023, Matsui had exercised his international free agent rights to be released from the Golden Eagles to seek a
Major League Baseball contract.
San Diego Padres On December 23, 2023, Matsui signed a five-year contract worth $28 million guaranteed with the
San Diego Padres of
Major League Baseball. The contract included an opt out after both the third and fourth seasons and an injury clause which would change the fifth and final year of the contract into a $7 million club option in the case of Matsui suffering a "serious elbow injury" during the length of the deal. ==International career==