Ideguchi was unveiled by Leeds this morning after arriving in England to undergo a medical yesterday.
United targeted the 21-year-old after watching him helping Japan qualify for this summer’s World Cup in Russia and a £500,000 deal with Gamba Osaka was struck at the beginning of December.
Leeds were initially doubtful that Ideguchi’s recent international appearances would be sufficient to earn him a work permit under Football Association rules but the governing body has granted his application.
Despite that, the midfielder is moving on a half-season loan to Spanish second division side Cultural Leonesa, a club who like Leeds are connected to Qatar’s Aspire Academy. United midfielder Ouasim Bouy spent the first half of this season with Leonesa.
Leeds have resisted the option of involving Ideguchi in their current Championship term and plan to integrate him into their first-team squad before the start of next season.
Ideguchi, the first Japanese player to sign for United, has been capped 10 times by Japan and his goal in a 2-0 win over Australia in August secured automatic qualification for the World Cup.
He spent four years as a professional with Gamba Osaka, making almost 100 appearances, and was named as the J League’s young player of the year in 2016.