| Taisei Ota 大勢 | |
| Position: | Pitcher |
| Team: | Yomiuri Giants |
| Number: | 15 |
| Bats: | Right |
| Throws: | Right |
| Birth Date: | 29 June 1999 |
| Birth Place: | Taka, Hyōgo, Japan |
| Debutleague: | NPB |
| Debutdate: | March 25 |
| Debutyear: | 2022 |
| Debutteam: | Yomiuri Giants |
| Statyear: | 2023 |
| Stat1label: | Win–loss record |
| Stat1value: | 4–3 |
| Stat2label: | Earned run average |
| Stat2value: | 2.82 |
| Stat3label: | Strikeouts |
| Stat3value: | 94 |
| Stat4label: | Saves |
| Stat4value: | 51 |
| Stat5label: | Holds |
| Stat5value: | 9 |
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is a professional Japanese baseball player. He is a pitcher for the Yomiuri Giants of Nippon Professional Baseball (NPB).[1] This is the first Japanese player use first name in the Yomiuri Giants.
On September 10, 2023, while pitching for Yomiuri's farm team, Taisei combined with Haruto Inoue to no-hit the Tokyo Yakult Swallows farm team. The no-hitter was the first combined no-hitter in the history of the farm team.[2]
Taisei represented Japan at the 2023 World Baseball Classic.[3]