Japanese left-hander Yusei Kikuchi has agreed to sign with the American League's Seattle Mariners, sources close to the matter revealed Monday.

Kikuchi, one of Japan's top pitchers, has agreed to a four-year deal with the Mariners, according to MLB.com. The 27-year-old lefty was posted to Major League Baseball on Dec. 3 by the Seibu Lions and had 30 days to negotiate a contract.

According to MLB.com, Kikuchi signed for an initial three years plus a player option in 2022, which can be replaced by an additional four-year guarantee totaling a seven-year stint overall.

The Mariners have yet to confirm the deal.

Kikuchi is the first Japanese player to be sent to the majors under the new posting system rules in effect since this postseason, whereby the Japanese team posting a player will receive a fee based on an agreed percentage of the value of the contract, bonuses and incentives.

He arrived in Los Angeles on Dec. 16 to negotiate a deal along with his high-profile agent, Scott Boras, who helped secure former Lion Daisuke Matsuzaka's blockbuster contract with the Boston Red Sox in 2006.

The Mariners have traded several notable veterans this off season while building a roster with younger prospects. Seattle general manager Jerry Dipoto expressed an interest in acquiring Kikuchi at the Winter Meetings two weeks ago.

Kikuchi will be the latest Japanese addition to the American League club, which has had at least one Japanese player on their roster every year since 1998, including Ichiro Suzuki, Hisashi Iwakuma, Kenji Jojima, Shigetoshi Hasegawa and Kazuhiro Sasaki.

Suzuki, who finished his 18th major league season as special assistant to the team's chairman, has been invited to play and coach during spring training and could join Kikuchi on the Mariners' roster when Seattle open their 2019 season against the Oakland Athletics at Tokyo Dome in March.

This season, Kikuchi helped Seibu finish with the best record in the Pacific League in Nippon Professional Baseball when he went 14-4 and struck out 153 batters over 163-2/3 innings.

He has a career record of 73 wins, 46 losses and one save with a 2.77 ERA.