Real Sociedad will pay €14 million plus add-ons to sign Brais Méndez from Celta Vigo, according to Mundo Deportivo.
The Galician player will become the second signing at the club after the arrival of Mohamed-Ali Cho.
Méndez has spent five seasons in the Celta first team. The left-footed player can operate as a playmaker or midfielder, and also on the wing.
Last season he scored five goals in 40 games in all competitions. His best scoring record came in the 2019-20 campaign, with nine goals in 36 games.
La Real have swooped for 25-year-old with Imanol Alguacil believed to be key in the move.
Méndez, who was the subject of other offers, including from the Premier League, is expected to arrive in time to start pre-season training with his new team-mates this coming Thursday at Zubieta.
Last November, Luis Enrique called him up for the Spain national team squad. The player from Pontevedra has faced Real Sociedad nine times in his career, eight times in La Liga and once in the Copa del Rey.
He will join the Basque club until 2028.