On April 16, 2019, Izumi debuted in the Pacific League against the Chiba Lotte Marines as a relief pitcher.[2] And in the match against the Orix Buffaloes on April 22, he pitched as a relief pitcher and became his first Winning pitcher.[3] In 2019 season, Izumi recorded with a 14 Games pitched, a 2–0 Win–loss record, a 1.96 ERA, a 3 Holds, a 18 strikeouts in 18.1 innings.
During the 2020 season, Izumi recorded 40 games pitched, a 0–1 win–loss record, a 2.08 ERA, an 8 Hold, and 28 strikeouts in 34.2 innings. In the 2020 Japan Series against the Yomiuri Giants, he was selected for the Japan Series roster.[4]
In 2021 season, Izumi had a 16-game scoreless streak from the start of the season, but slowly lost his form and lost his chance to pitch in June. He finished the season with a record of 31 games pitched, a 0–2 Win–loss record, a 2.73 ERA, a 6 Holds, and a 30 strikeouts in 26.1 innings.[5]
In 2022 season, he finished the regular season with a 30 Games pitched, a 0–2 Win–loss record, a 3.73 ERA, a 6 Holds, and a 25 strikeouts in 29 innings.
In 2023 season, Izumi only pitched in three games in the first league.