Seattle Mariners Assign Intriguing Veteran Tomo Otosaka to Triple-A Tacoma Rainiers

Otosaka, 31-years-old, spent eight years in his native Japan with the Yokohama DeNA BayStars from 2014-2021. He made his debut for the major league club in 2014. He was an up-and-down player with the organization. Every single year he played in the majors, he also spent time with the BayStars' farm team. The 5-foot-11, 182-pound outfielder played a career-high 97 games with Yokohama's major league club in 2019. He scored 19 runs that season and hit eight doubles, two triples, two homers and had 17 RBIs. He slashed .245/.313/.359 with a .671 OPS.

Otosaka has spent parts of 2022-25 in the Mexican League and Venezuelan Winter League. He also played for the Revolution in 2023 and 2025. In 2023, he scored 86 runs in 111 games and hit 21 doubles, one triple, two home runs and registered 48 RBIs. He stole 42 bases on 51 attempts and had a slash line of .330/.441/.408 with an .848 OPS.

In nine games with York this season, Otosaka scored 11 runs and hit six doubles, one homer and eight RBIs. He slashed .405/.500/.649 with a 1.149 OPS.

"I’m extremely happy for Tomo," Revolution manager Rick Forney said in a news release. "He’s such a good person and a great teammate. He’s an extremely hard worker and is very deserving of this opportunity."

Otosaka's signing is an interesting development for the Mariners. For years, the club was one of the most prominent teams when it came to recruiting international talent out of Japan. They were one of the finalists for Shohei Ohtani when he first came to the U.S. from Japan in the 2017 offseason, but he signed with the Los Angeles Angels. Seattle also expressed interest this offseason in signing Roki Sasaki, but didn't make it to the final crop of teams in pursuit of his services. He signed with the Los Angeles Dodgers.

Otosaka doesn't have a pedigree near what Ohtani and Sasaki had when they came stateside. But Otosaka starting in Triple-A could open the door to him making his major league debut soon. If he does well, or carves out a spot on the major league roster, it could re-open a pipeline that has been slow-moving in recent years.

Related Minor League Baseball stories

MARINERS TOP 100 PROSPECT COLE YOUNG NAMED MINOR LEAGUE PLAYER OF THE WEEK: One of the Mariners most experienced elite minor leaguers has started to heat up after a slow start to 2025. CLICK HERE

MARINERS FIRST-ROUND PICK JURRANGELO CIJNTJE IMPRESSES IN LATEST START: The switch-pitching, first-round draft pick had yet another solid outing with the High-A Everett AquaSox. CLICK HERE

OFTEN-USED MARINERS RELIEVER ON INJURED LIST FOR TRIPLE-A TACOMA: The heavily-used Rainiers southpaw will be out for several weeks with a left lat strain. CLICK HERE