Muto was a bit-part player at Newcastle last season and played just six minutes of Premier League football after the campaign restarted in June.
Steve Bruce has been prepared to move him on in the ongoing transfer window and the club are now on the verge of loaning him out.
A deal is in place between Newcastle and Eibar for Muto to move to the Spanish club on a season-long loan.
And according to German outlet Fussball Transfers, the Japanese will sign a loan contract with the Spanish club today to seal the move.
The forward is hoping to revive his career in Spain after struggling to adapt to the Premier League and Newcastle.
The Magpies would have preferred to sell him but the loan agreement between the two clubs does not have a purchase option.
Newcastle signed Muto from Mainz for around €11m in 2018 but he scored just twice in 28 appearances for the club.
He still has two years left on his Newcastle contract.