Artwork wrapping around the exterior surface depicts a humpback whale swimming in the water and blowing water out of its blowhole.
This mug is finished in 3 tones: light brown, beige, and white.
There are no manufacturer's markings on this mug but based on its style I strongly suspect it was manufactured by Otagiri.
Condition note: there is some minor wear on the bottom rim. Please see the last photo for a look at this.