The Astros have landed the offseason’s top Japanese pitcher. Houston and right-hander Tatsuya Imai have agreed to a deal, CBS Sports HQ’s Jim Bowden confirmed Thursday. It’s a three-year contract that could be worth up to $63 million, but Imai has opt outs after each season. The team has not yet announced the signing. Imai’s 45-day posting window was set to expire at 5 p.m. ET on Friday.
Imai, 27, has played his entire career with the Seibu Lions of Japan’s Nippon Professional Baseball. He has been one of NPB’s top starters since 2021 and, in 2025, he threw 163⅔ innings with a 1.92 ERA and 178 strikeouts. Imai struck out 28% of the batters he faced in the league where the average is a 19% strikeout rate. The MLB average was 22% strikeouts in 2025, for reference.
We ranked Imai as the 12th-best free agent available this offseason and the fifth-best starting pitcher. Here’s what you need to know about the right-hander:
Relative to how front offices view hitters transferring from NPB, pitchers are a near-certain quantity. There are too many success stories to fixate on the differences in the ball and the schedule or to suggest it’ll have a devastating effect on the talent in question. That’s good news for Imai’s stock. He’s fresh off a dominant season that saw him post a 1.92 ERA and a 3.96 strikeout-to-walk ratio across 163 innings. He possesses mid-90s velocity and a forkball-like slider he delivers from a low release point. Imai isn’t far removed from struggling with his command (it took until his seventh professional season for him to walk fewer than four batters per nine innings), but teams confident in his strikethrowing ability could envision him being at least a No. 3 starter as soon as next spring.
As the scouting report suggests, Imai is not considered on par with Yoshinobu Yamamoto, who was seen as an instant ace who could front a contender’s rotation from Day 1. Imai needn’t be Yamamoto to be a valuable member of a rotation, however. He’s only 27 with plenty of peak years ahead of him, and mid-to-upper-90s gas always plays.
Imai was made available to MLB teams through the posting process and the Astros owe the Seibu Lions a posting fee that is based on the size of his contract. Here is the posting fee structure:
- Contract worth less than $25 million: 20% of contract value
- Contract worth $25 million to $50 million: $5 million plus 17.5% of amount over $25 million
- Contract worth more than $50 million: $9.275 million plus 15% of amount over $50 million
The posting fee does not count against the competitive balance tax, though it is a lot of real money that has to be paid to the Lions in short order. The signing must be complete by the 5 p.m. ET on Friday. Physical passed, contract signed, the works. An agreement and a handshake is not enough.