Juanjo Nieto has departed from Celje after two seasons to rejoin his former club in Spain, Castellón. The Spanish second division side confirmed the right-back has joined on a contract until June 30, 2029. The transfer did not involve a fee. For the 31-year-old, this is a return to the club where he began in the youth academy thirteen years prior. Castellón highlighted that Nieto has extensive experience and knowledge of the Spanish second division. In his last season in the Prva Liga, Nieto made 25 appearances, scored 5 goals, and provided 3 assists. His market value is €400k, according to Transfermarkt.