The Ryukyu mouse has a dark grey back and pale underside. A Taiwan museum record describes it in lowland fields, feeding on seeds and plant roots.
The back is dark grey and the belly ash-white. The tail is also two-toned, with different colors on its upper and lower sides.
The museum record describes it in lowland Taiwan fields, where it feeds on roots, rhizomes, and seeds.
An extinction-risk assessment has not been added yet.