This 'Dot Roller' is a Hokkaido roller featuring 6 distinctive raised dots. There are 3 dots on each side of the float.  The barrel has 2 dots and each of the ears has 2 dots.

These dots may have occured as a result of holes in the mold.

There is also a very pronounced mold line where the two halves of the mold met.

This float has WP #25 'Dai' 大 stamped on the seal.  It seems reasonable to assume that Daiichi Glass Company was the float maker.

There's a very nice molded texture on the surface of the glass, too.

Found on Hokkaido Island, Japan.