楽天は１７日、新監督として前ロッテ監督の吉井理人氏（６１）が就任することを発表した。吉井氏は宮城・仙台市内で三木谷浩史オーナー（６１）と会見に臨んだ。背番号「８１」のユニホームに袖を通した吉井氏は「大きな仕事を任されたことに、野球人としてすごくうれしかった」と喜びを口にした。

He admitted to having some hesitation about taking on the role, but now confessed his burning determination, saying, "I've made up my mind. I'm ready to fight." He continued, "I want everyone to reaffirm their strong determination to win."

During his playing career, Yoshii experienced three league championships and two Japan Series titles as pitcher with Kintetsu and Yakult. He played for three MLB teams, the Mets, Expos, and Rockies, and recorded a total of 121 wins in Japan and the US. After ending his playing career with Lotte in 2007, he started his coaching career in 2008 as the first-team pitcher coach for Nippon-Ham. He developed top-class pitcher such as Yu Darvish (Padres) and Shohei Ohtani (Dodgers). His skills were so highly regarded that he also served as pitcher coach for Samurai Japan. In 2022, he coached Roki Sasaki (Dodgers) as a pitching coordinator. From 2023, he served as the manager of Lotte for three years, and in his first year as manager, he led the team from fifth place the previous year to second place.

Rakuten Eagles was in contention for first place until mid-April this season, but then their performance plummeted. After 63 games, they were struggling with a record of 23 wins, 39 losses, and 1 tie, a deficit of 16 games. From May onwards, they also made changes to the coaching staff. However, no dramatic improvement was seen. At 1am on the 10th, after the game against The Giants (Rakuten Eagles Mobile), when their deficit reached 15 games, they made a surprise announcement that manager Miki would be taking a leave of absence. Since the announcement, head coach Shiokawa has been serving as acting manager. Aiming for further progress, they have brought in Mr. Yoshii as the new manager midway through the season. This marks the birth of a new manager who was brought in from outside the organization at an unusual time.