On the 31st, the deadline for trades and other reinforcements in professional baseball reached its roster. Seibu Lions entered the day with the maximum number of players allowed under their roster, 70.

On the 30th, the day before the deadline, the team announced that they had signed a regular player contract with catcher Ryosuke Korezawa, who is in his fourth year as a developmental player. After signing the regular player contract with Korezawa that day and concluding the press conference, Director and General Manager Hiroike spoke to reporters, emphasizing a certain degree of satisfaction, saying, "I don't know if I can say with certainty that we have assembled a team capable of winning the championship, but we have done what we needed to do to reach this day."

He then added, "Pacific League is strong, so naturally, I think we'll face tough battles ahead, but I hope we can somehow make it through to the fall with this lineup. We also need to focus on various strategies and physical condition management to try and create another good momentum," showing the team's determination to aim for their first league championship since 2019.