Small Japanese field mouse

The small Japanese field mouse (Apodemus argenteus) is a species of rodent in the family Muridae. It is endemic to Japan, spanning from Hokkaido to Kyushu and is similar to its larger counterpart, Apodemus speciosus.

Anatomy
The body length is 65–100mm, tail 70–110mm, weight 10–20g. Although it is similar to a large Japanese field mouse, the small mice have slightly longer tails then the body, opposite to the large mice.