He spent some time in Japan where he collected mammals for the British Museum,[2] including the type specimen of this vole.

The ever-growing molars in C. smithii are now believed to be independently derived from a rooted Craseomys ancestor endemic to Japan.

[4] Phaulomys is now considered a subgenus of Craseomys, and contains this species, the Japanese C. andersoni, and the Korean C. regulus, although the exact taxonomy remains unsettled.

[5] Smith's vole is found on the Japanese islands of Dogo, Honshu, Kyushu and Shikoku.

It is a common species in chosen habitat but some of its populations are fragmented by road development, land reclamation, dam building and deforestation.