He has previously played in MLB for the Seattle Mariners, Toronto Blue Jays, and Houston Astros, and in Nippon Professional Baseball (NPB) for the Saitama Seibu Lions.

[2][3] In October 2009, Kikuchi sparked controversy when it was announced that he was considering bypassing the amateur draft in Japan for the NPB and signing with an American Major League Baseball club.

[8] Japanese news service reports also identified scouts from the Los Angeles Dodgers, Seattle Mariners, New York Mets, Cleveland Indians, Chicago Cubs, San Francisco Giants,[9] Detroit Tigers, Atlanta Braves and New York Yankees watching Kikuchi in tournaments.

[8][10] Hanamaki Higashi manager Hiroshi Sasaki submitted paperwork to the high school baseball federation in Iwate Prefecture on Kikuchi's behalf, stating his desire to turn pro.

The move opened the way for professional teams to make contact with Kikuchi in a race to secure his services.

With the submission of the paperwork, Kikuchi was open to be named in the Japanese baseball draft, which began on October 29, 2009.

[17] Kikuchi would have been the first Japanese high school player to bypass the domestic amateur draft to come to MLB.

[21] After the 2011 season, Seibu announced that Kikuchi would join the Melbourne Aces of the Australian Baseball League (ABL).

[23] On December 3, 2018, Seibu announced it was allowing Kikuchi to enter the posting system to play in Major League Baseball (MLB),[24] with the 30-day period starting a month later.

On July 29, 2024, Kikuchi was traded to the Houston Astros in exchange for Jake Bloss, Joey Loperfido, and Will Wagner.

[35] On August 2, in his team debut against the Tampa Bay Rays, Kikuchi became the first Japanese-born starting pitcher in Astros franchise history.

[36] He also tied a franchise record with eight consecutive strikeouts, of which that streak ended on a full count walk to Yandy Díaz.