Ohka became the first player from Japan to play for the Red Sox when he debuted in 1999. During the middle of the 2001 season, Ohka was sent to Montreal for the veteran
closer Ugueth Urbina. Ohka had a mildly successful run with the Expos. His most productive season came with the Expos in , when he posted 13–8 with 118 strikeouts and a 3.18 ERA. In June 2004, Ohka's right forearm was broken when he was hit by a line drive off the bat of
Carlos Beltrán in
Kansas City. Ohka underwent major surgery and was out until mid-September. He finished 3–7 with a 3.40 ERA in 15 starts.
Washington Nationals and Milwaukee Brewers in 2005 As the Expos moved to
Washington, D.C. for the 2005 season, Ohka was part of a starting rotation that included
Liván Hernández,
Esteban Loaiza and
Tony Armas Jr. Ohka was involved in an incident with Washington manager
Frank Robinson. Ohka protested being removed from a game, a move which resulted in an undisclosed fine from the team. On June 10, 2005, the Washington Nationals traded Ohka to the Milwaukee Brewers for
second baseman Junior Spivey. In Ohka's first game with his new club on June 14, he threw a shutout against the
Tampa Bay Devil Rays during
interleague play. in 2006
Toronto Blue Jays On January 23, 2007, the right-hander reached a tentative agreement with the Toronto Blue Jays on a one-year contract. The agreement was made official on January 25, 2007, and the contract was announced to be worth $1,500,000. Ohka could earn an additional $1,500,000 in incentives. Incentives are usually based upon
innings pitched or game appearances.
St. Louis Cardinals and Seattle Mariners On June 7, after compiling a 2–5 record in 10 starts, the Toronto Blue Jays designated Ohka for assignment and subsequently released him on June 18. On June 19, 2007, he signed a minor league contract with the
St. Louis Cardinals. He was released by the Cardinals on July 3, 2007, after going 0–2 with a 6.87 ERA in 3 starts for their Triple A team, the
Memphis Redbirds. Ohka then signed a minor league contract on July 13, 2007, with the
Seattle Mariners. Ohka was released by Seattle on August 5, 2007, after going 0–3 with a 10.32 ERA in four outings, allowing 26 runs in innings with the
Tacoma Rainiers, Seattle's AAA affiliate.
Chicago White Sox On February 21, 2008, Ohka signed a minor league contract with the
Chicago White Sox, but did not play in the major leagues that year. He became a free agent at the end of the season. In an eight-year career, Ohka has compiled a 48–57 record with 538
strikeouts and a 4.04
ERA in 943
innings.
Cleveland Indians On December 5, 2008, Ohka signed a minor league contract with the
Cleveland Indians with an invitation to Spring Training. On March 15, he was reassigned to the minor league camp. He was called up to the majors on May 30. He became a free agent following the season.
Return to Japan On April 6, 2010, Ohka signed a contract with his former team, the
Yokohama BayStars in Japan. He pitched for them through 2011. In 2013, he reinvented himself as a
knuckleball pitcher and played for the
Toyama Thunderbirds of the
Baseball Challenge League.
Toronto Blue Jays Ohka signed a minor league contract with the
Toronto Blue Jays on December 11, 2013. He was a non-roster invitee to spring training, but was reassigned to minor-league camp on March 2, 2014, without making an appearance. He was released by the Blue Jays at the end of spring training.
Bridgeport Bluefish On April 30, 2014, Ohka signed with the
Bridgeport Bluefish of the
Atlantic League of Professional Baseball. In 26 starts for Bridgeport, he compiled a 7–12 record and 5.15 ERA with 49 strikeouts across innings pitched. Ohka became a free agent following the season.
Fukushima Hope Ohka returned to Japan and played with the
Toyama Thunderbirds and
Fukushima Hope of the semi-pro
Baseball Challenge League for the 2015 season.
Baltimore Orioles On December 15, 2016, the
Baltimore Orioles signed Ohka to a minor league contract. He was released on April 1, 2017, as the Orioles' spring training came to a close. ==Milestone==