This is a beautiful taller than average mug with artwork wrapping around the exterior depicting 6 etched horses.
This mug features a tri color design on its exterior surface and handle with the lower 1/2 being finely speckled brown, the next 1/4 a lighter more coarsely speckled brown, and the upper 1/4 beige with scattered speckles. The interior is the same color and speckle pattern as the upper 1/4.
Though no markings are present, I strongly suspect this was manufactured by Otagiri.
Condition note: there is some of the darker brown paint from the lower 1/2 present where the top of the handle connects to the body of the mug. Please see the red arrow pointing to this in the 1st photo.