The transfer fee discussed for Kaishu Sano has been up to 60 million euros. Mainz 05's sporting director, Christian Heidel, stated that the club is not obligated to sell Sano and can afford to retain him. Heidel added that if the player stays, many people in and around the team and club will be happy. However, the sporting director also emphasized that, consistent with the club's policy, they would have to consider an offer if it were extraordinary.

Newcastle United are considering Kaishu Sano from FSV Mainz, a 25-year-old defensive midfielder, as an alternative to another target, Angelo Stiller from VfB Stuttgart. The Japanese international has 16 caps and one goal for his country and has been previously linked with numerous financially strong clubs. The Premier League club is prepared to offer up to 55 million euros for him. Sano joined Mainz in July 2024 for a reported €2.5 million, has a contract until 2028, and has a current market value of €40.00m, according to Transfermarkt. In recent months, Mainz's asking price has reportedly been in the €50-60 million range. Newcastle has not yet made an approach for Sano.