Tatsuya Imai

Tatsuya Imai plays for the Houston Astros. He signed a 3-year, $54 million deal via the posting system in January 2026 and made the Opening Day rotation in his MLB debut season.

Through April 2026, Imai has made 2 starts with a 4.32 ERA, 1-0 record, 13 strikeouts, and a 1.56 WHIP. After a rough Opening Day (March 29 vs. Angels: 2.2 IP, 4 BB), he bounced back with 9 strikeouts in 5.2 IP against the Athletics on April 4. His K/9 of 14.04 ranks among the best for any MLB starter. Check the stats box above for the latest numbers.

Through April 27, Imai is 1-0 with a 7.27 ERA, 13 strikeouts, and a 2.08 WHIP across 3 starts (8.2 IP). The 7.27 ERA looks rough, but the underlying K/9 of about 13.5 ranks among the very best for any MLB starter — the swing-and-miss arsenal is fully translating from NPB. The gap between elite strikeout rate and elevated ERA is entirely the walk rate (11 BB, BB/9 ~11.4); the Astros' development plan is targeting Zone% improvement while preserving the chase-inducing forkball.

Imai's 2026 ERA stands at 7.27 with a K/9 of approximately 13.5 (13 strikeouts in 8.2 innings) through 3 starts as of April 27. The K/9 is among the top tier for MLB starters — well above the league average of about 8.5. The path to ERA recovery runs through walk prevention: in NPB he posted a 1.92 ERA in 2025 and won the 2024 strikeout title with 187 K, so the run-prevention ceiling is real once command catches up to the stuff.

Imai works primarily with a mid-90s (150km/h+) four-seam fastball. He pairs it with a sharp, diving forkball (splitter-style) and a slider. His ability to tunnel the forkball off the fastball generates elite swing-and-miss rates — evidenced by 13 strikeouts (K/9: 14.04) in his first two MLB starts.

Imai is a power right-hander who works with a mid-90s (150km/h+) fastball as his primary pitch. He pairs it with a sharp, diving forkball and a slider to get swings and misses against both lefties and righties. In 2026, opponents are hitting .200 against him with a 14.04 K/9 rate. Improving his walk rate (7 BB in 8.1 IP) is the key to becoming a front-of-rotation arm.

In 7 seasons with the Seibu Lions (2018–2025), Imai claimed the NPB strikeout title in 2024 and posted a career-best 1.92 ERA in 2025. After recovering from a shoulder injury early in his career, he became the undisputed ace of the Lions from 2022 onward. He was also a WBC Japan national team candidate in 2023.

Tatsuya Imai was born on September 18, 1998. He is 27 years old at the start of the 2026 MLB season — arriving in the majors at an ideal age after seven years of seasoning in NPB.

Imai's next scheduled start and his most recent outing (IP, K, ER, pitch count) are updated in the stats box at the top of this page and on the dedicated "Today" page. The Today page also includes pitch usage by type (mid-90s fastball, diving forkball, slider), swing-and-miss rates, splits vs RHB/LHB, and a Unico AI breakdown. Live in-play updates run during the game; final results are posted by 18:00 JST.

View Tatsuya Imai's today start details→

The strikeout-or-walk profile is the answer. Through April 27, Imai's 13.5 K/9 ranks among MLB's elite, but his 11.4 BB/9 puts him in the bottom tier for command. When walks pile up, even a modest hit rate produces multi-run innings — and the resulting short outings (sub-3 IP starts) keep his ERA elevated even when his stuff is overpowering. The Astros' development priority is improving Zone% (in-zone pitch rate) and CSW% (called strike + whiff rate). If he can keep his K/9 above 10 while cutting BB/9 to the 4 range, his ERA will drop into the 3-4 range — the typical landing spot for high-strikeout starters with NPB-caliber pedigree.

Imai is firmly in the AL Rookie of the Year (ROY) conversation as a top-tier candidate in his MLB debut season. Three reasons: (1) His K/9 of about 13.5 (through April 27) is among the best for any MLB starter and historic territory for a rookie. (2) The mid-90s rising four-seam fastball paired with a sharp diving forkball is generating elite swing-and-miss in MLB — confirming the arsenal is "MLB-ready" rather than NPB-only stuff. (3) His NPB resume (2024 strikeout title with 187 K, 2025 ERA leader at 1.92) frames the early MLB strikeout rate as legitimate skill, not small-sample variance. The gap is walks (BB/9 around 11). The Astros' development staff is targeting Zone% improvement; if command catches up by midseason and he reaches 120-150 IP with an ERA in the 3-4 range, he becomes a serious challenger for the November ROY vote.

Imai (Astros, age 27, MLB year 1) and Yamamoto (Dodgers, age 27, MLB year 3) are the headline Japanese right-handers in MLB. Similarities: (1) Both won NPB strikeout titles (Imai 2024; Yamamoto 2019, 2020, 2021), (2) both pair a mid-90s fastball with a high-diving secondary (Imai forkball, Yamamoto splitter), (3) both made the MLB jump at age 27, the prime power-pitcher window. Differences: contract size (Imai 3yr/$54M vs Yamamoto 12yr/$325M), MLB experience (Imai year 1 vs Yamamoto year 3), and pitch-mix style (Imai is K/9-driven power, Yamamoto is the more complete strike-thrower). 2026 early-season comparison: K/9 ~13.5 (Imai) vs ~10 (Yamamoto); ERA 7.27 (Imai) vs sub-3 (Yamamoto). Imai leads in raw strikeout rate; Yamamoto dominates in stability and command. Visit Yamamoto's page for direct year-by-year, pitch-mix, and platoon-split comparisons.

View Yoshinobu Yamamoto's stats page→