Roki Sasaki: Complete Career Stats, NPB Records, and MLB Profile (Updated September 2026)

By The Yakyu Analyst | Japan Baseball Lab

Table of Contents

1. Introduction
2. Early Life & Background
3. Ofunato High School (2018–2020)
4. NPB Career: Chiba Lotte Marines (2021–2024)
5. The Perfect Game: April 10, 2022
6. MLB Career: Los Angeles Dodgers (2025–present)
7. International Stage
8. Records and Milestones

1. Introduction

The Dodgers’ 2025 rotation featured three Japanese starters simultaneously — Shohei Ohtani, Yoshinobu Yamamoto, and Roki Sasaki — a concentration of Japanese pitching talent on a single MLB roster that would have been unimaginable before Hideo Nomo filed his retirement papers in 1995. Of the three, Sasaki arrived with the most raw upside and the most uncertainty. A pitcher who had thrown a perfect game at age 20, touched 165 km/h (102.5 mph) in high school, and posted a 51.5% forkball whiff rate in NPB also came with a shoulder injury history, a ceiling-versus-floor profile that scouts debated intensely, and a MLB debut season that confirmed both the talent and the concerns.

Through September 2026 — in what is effectively his first full MLB season after his 2025 debut was cut short by a right shoulder impingement — Sasaki is in the process of resolving that debate. His season line (6-6, 4.57 ERA through August 26) does not capture the trajectory: a rocky start (6.35 ERA through five April starts) followed by a documented mechanical correction that has produced steadily improving results through the summer. The underlying data — a 99.5 mph four-seam fastball that touches 102, a forkball with a 44%+ whiff rate, an improving chase rate (27.0% to 34.7%) — points toward a pitcher whose surface line has not yet caught up with his stuff quality.

For the biomechanical analysis of his forkball and pitching mechanics, see our companion piece: [Link: Roki Sasaki’s Forkball — Spin Axis, RPM, and the Physics of an 80-Grade Pitch]

2. Early Life & Background

Sasaki was born on November 3, 2001 in Rikuzentakata, Iwate Prefecture — a coastal city in Japan’s Tohoku region that was devastated by the 2011 Tōhoku earthquake and tsunami. He was nine years old when the disaster occurred. His father and paternal grandparents were among the victims — a biographical fact that Sasaki has discussed sparingly in public but that frames the personal context of his subsequent baseball career in a way that cannot be ignored.

He was raised primarily by his mother and began playing baseball in elementary school in Rikuzentakata. His early development as a pitcher attracted local attention by middle school, and by the time he was selecting a high school program, he was already being discussed as a potential NPB-level talent. He chose Ofunato High School — not a nationally elite baseball program — over several stronger programs, a decision that, like Yamamoto’s choice of Miyakonojo High School, prioritized a specific development environment over immediate national competition exposure.

3. Ofunato High School (2018–2020)

Sasaki’s three years at Ofunato High School produced one of the most analytically significant high school pitching careers in NPB draft history — and one of its most controversial endings.

Velocity Progression and Records

Sasaki’s fastball development at Ofunato was extraordinary even by the standards of elite high school pitching:

His 163 km/h reading — recorded at age 17, breaking Ohtani’s national high school record of 160 km/h — earned him the nickname “Monster of the Reiwa Era” (令和の怪物), combining the imperial era designation that began in 2019 with the established baseball shorthand for a generational pitching talent. The nickname has remained his primary identifier throughout his professional career.

The 194-Pitch Regional Game

In a regional qualifier for the Summer Koshien tournament, Sasaki threw a 12-inning complete game with 21 strikeouts on 194 pitches — a performance that generated substantial analytical attention for two reasons simultaneously. First, it was a historic individual pitching achievement at the amateur level. Second, it illustrated precisely the arm health concerns that Japan Baseball Lab covers in our Koshien analysis: 194 pitches by an 18-year-old in a single game represents a UCL stress load that would not be permitted in any professionally managed development environment. See: [Link: Koshien Tournament Format and the Arm Health Crisis]

The Controversial Tournament Non-Start

Despite the 194-pitch regional qualifier performance, Sasaki did not start Ofunato’s final regional game — the one that would determine whether the team qualified for Koshien. Head coach Hiroshi Kudo made the decision not to start Sasaki, citing arm protection concerns. The team lost. Sasaki, who had been warming up in the bullpen and reportedly wanted to pitch, did not appear in the game.

The decision became a national story in Japan. Kudo was criticized by some commentators for costing the team their Koshien opportunity; he was praised by others — including most sports medicine professionals who commented publicly — for making the correct medical decision. In the context of Japan Baseball Lab’s ongoing coverage of pitcher arm health in Japanese baseball, Kudo’s decision stands as one of the few documented instances of a high school coach explicitly prioritizing a pitcher’s long-term health over short-term competitive outcomes. Sasaki has publicly stated that he respects the decision in retrospect.

2019 NPB Draft

The Chiba Lotte Marines selected Sasaki with the first overall pick of the 2019 NPB Draft. Cognizant of his workload history and the shoulder impingement he had experienced during his high school years, the Marines made an unusual organizational commitment: they would not allow him to pitch professionally in his first season (2020) and would use him sparingly in his second (2021). This deliberate development timeline — prioritizing arm health over immediate competitive output — was, at the time, a significant departure from standard NPB organizational practice.

4. NPB Career: Chiba Lotte Marines (2021–2024)

Year-by-Year Statistics

★ Perfect game season. Sources: MLB.com official bio, Wikipedia, Sports Info Solutions NPB Scouting Report (February 2024), RotoWire. 2024 IP estimated from available game log data.

Reading the Record

2021: The Managed Debut. Sasaki’s 11-start debut (2.27 ERA, 68 K in 63.1 IP) was the product of a deliberate organizational load management program. The Marines capped his outings at a maximum pitch count and shut him down before the end of the season. The results — including a 0.98 WHIP at age 19 in his first professional exposure — were immediately impressive.

2022: The Historic Season. Sasaki’s age-20 campaign is the most statistically remarkable of his NPB career. His 2.02 ERA and 12.0 K/9 across 20 starts were elite by any standard; the perfect game on April 10 and the subsequent eight perfect innings in his next start placed him in a category of pitching performance that has no modern equivalent. His 173 strikeouts in 129.1 innings — a K/9 of 12.0 — led the Pacific League in strikeout rate by a substantial margin. His WHIP of 0.78 is the third-lowest single-season figure in NPB history.

2023: Elite Rate Stats, Limited Volume. Despite pitching only 91 innings due to injury management, Sasaki’s 2023 rate statistics were his career best: 13.4 K/9, 1.78 ERA, 0.77 WHIP. His forkball posted a 51.5% whiff rate — one of the highest documented for any pitch by any pitcher at any professional level. The injury limitation was the only analytical concern; when healthy and pitching, there was arguably no pitcher in the world producing more dominant per-inning results.

2024: The Velocity Question. Sasaki’s final NPB season introduced the durability and velocity concerns that follow him into MLB. His fastball velocity dropped from triple digits to the upper-90s, his K% declined from 39.1% to 28.6%, and his ERA rose to a still-excellent 2.35. RotoWire noted the possibility that he was “simply getting worse rather than making a conscious decision to stay healthy” — a legitimate concern that his 2025–26 MLB data has partially addressed by showing the velocity capable of returning to 99-102 mph when mechanically correct.

5. The Perfect Game: April 10, 2022

On April 10, 2022, at ZOZO Marine Stadium in Chiba City, Sasaki retired all 27 Orix Buffaloes batters he faced in a 6-0 Chiba Lotte Marines victory — becoming the 16th pitcher in NPB history to throw a perfect game, and the first since Hiromi Makihara in 1994.

The statistical context makes this perfect game historically unique. He struck out 19 of the 27 batters he faced — tying the NPB record for strikeouts in a single game (previously set by Hideo Nomo in his 1990 debut season). Of those 19 strikeouts, 13 came consecutively — a world record for consecutive strikeouts in a professional game, surpassing the previous record of 10 held by Tom Seaver (MLB, 1970). He threw 102 pitches. He was 20 years, 159 days old — the youngest pitcher to throw a perfect game in NPB history.

In his next start, on April 17 against the Hokkaido Nippon Ham Fighters, he threw eight additional perfect innings before allowing a hit in the ninth. The combined 17 consecutive perfect innings and 33 strikeouts across two starts produced a two-week period that stands alone in modern Japanese baseball history.

The game was attended by 22,431 fans at ZOZO Marine Stadium. Given the coastal wind conditions at ZOZO (documented in our stadium science piece: [Link: NPB Stadium Science — How Ballparks Shape Player Stats]), the atmospheric conditions of that specific night — relatively calm winds, moderate temperatures — contributed to pitching conditions that were favorable but not dramatically so. The performance was not an artifact of park conditions.

6. MLB Career: Los Angeles Dodgers (2025–present)

Sasaki signed with the Los Angeles Dodgers in January 2025 via the posting system. Because he was under 25 years old at the time of posting, he was subject to international bonus pool restrictions — limiting his signing bonus to approximately $6.5 million rather than the open-market value his talent would otherwise command. This restriction was a specific consequence of MLB’s collective bargaining rules for international players under 25, and it was one reason multiple teams competed for his signing despite the below-market compensation structure.

MLB Statistics

*2026 stats as of approximately September 7, 2026. Sources: Wikipedia, RotoWire, FanGraphs, Blue Unicorn Analytics (blueuni17.com), Baseball Reference. Some 2025 figures estimated from available game log data; 2025 season was fragmented between starting and relief roles.

2025: Debut, Injury, and World Series

Sasaki made his MLB debut on March 19, 2025 in Tokyo — the Dodgers’ Opening Series against the Cubs — pitching before a Japanese crowd in a game that received substantial media coverage in Japan. His first eight starts produced a 4.72 ERA and 1.49 WHIP across 34.1 innings, with a 29:22 K:BB ratio that reflected both his elite swing-and-miss capability and a walk rate that was unsustainable at the MLB level. He was placed on the injured list with a right shoulder impingement and did not return as a starter in 2025.

He returned as a reliever in late September after a mechanical adjustment that, per multiple sources, unlocked his velocity and movement profile. In the postseason — pitching in short stints out of the bullpen — he was dominant, contributing to the Dodgers’ 2025 World Series championship against the Toronto Blue Jays. He became a World Series champion in his first professional season.

2026: The Development Season

The 2026 season is, as Blue Unicorn Analytics noted, effectively Sasaki’s “Dodgers Year 1” — his first attempt at a full MLB starting season. Through five April starts he posted a 6.35 ERA and 1.81 WHIP across 22.2 innings. The underlying pitch data told a different story: a 99.5 mph four-seam fastball, a forkball with a 44%+ whiff rate, and a walk rate (5.16 BB/9) that was the primary correctable problem.

FanGraphs documented a mechanical correction mid-season that produced measurably better results. His chase rate improved from 27.0% to 34.7%, and his seven fastest pitches of the season — all 99.5 mph or higher — came in a single start against the Phillies, with 14 of his 22 fastest pitches of the year over a three-start span. The velocity was not gone; the command had been the variable. His overall trajectory — high-end stuff with command volatility — matches the textbook NPB-to-MLB adjustment curve that Yu Darvish and Masahiro Tanaka traced before stabilizing.

7. International Stage

WBC 2023

Sasaki was named to Japan’s WBC roster for the 2023 tournament. He made two starts, going 1-0 with a 3.52 ERA and 11 strikeouts across 7.2 innings. His most documented WBC appearance was the semifinal against Mexico on March 20, 2023 — the same game in which Munetaka Murakami hit the walk-off double. Sasaki started and pitched four innings, striking out six including Randy Arrozarena on a 102 mph fastball followed by a splitter that produced one of the WBC’s most-shared video clips. Japan won the championship, defeating the United States 3-2 in the final.

WBC 2026

Sasaki participated in WBC 2026 as a starter for Japan. The tournament results — Japan was eliminated in the quarterfinals — were a disappointing outcome for the defending champions, though Sasaki’s individual performance was reported positively. The tournament came during his pre-season preparation and is not considered to have had a documented effect on his 2026 regular season performance.

8. Records and Milestones

Continue exploring:

• [Link: Roki Sasaki’s Forkball — Spin Axis, RPM, and the Physics of an 80-Grade Pitch]
• [Link: The Japanese Splitter — Grip Physics and Why It Breaks Differently]
• [Link: Koshien Tournament Format and the Arm Health Crisis]
• [Link: The Complete Guide to Japanese Baseball] (Pillar Page)

Stats last updated: approximately September 7, 2026. NPB statistics sourced from MLB.com official bio and Wikipedia. MLB statistics sourced from Wikipedia, RotoWire, FanGraphs, Baseball Reference, and Blue Unicorn Analytics. Perfect game data from Wikipedia’s dedicated article. Pitch analytics from Sports Info Solutions NPB Scouting Report (February 2024) and FanGraphs (June 2026). This page will be updated as the 2026 season concludes. Correspondence: [email protected]