Mainz have signed Japan defensive midfielder Kaishu Sano on a four-year contract until 2028, the Bundesliga club said on Wednesday. Sano, 23, arrives from J-League club Kashima Antlers for an undisclosed fee and is set to join the team on July 21. Mainz started pre-season training on Wednesday. “We will support Kaishu both on and off the pitch to realise his full potential here in the Bundesliga,” Mainz board member for sport Christian Heidel said.