Based on its similarity to these two species, it is hypothesized that the ancestor of the frosted myotis evolved to the south of Japan, and its range expanded northwards over time.

The fur of its back is brackish brown, with conspicuous frosted tips.

The fur is velvety in texture, dense, and short, with individual hairs approximately 5.5 mm (0.22 in) long.

It meets the criteria to be listed as endangered because its extent of occurrence is less than 5,000 km2 (1,900 sq mi), its range is severely fragmented, and its habitat is projected to decline in extend and quality.

Some of the main threats facing this species are habitat destruction and forest fragmentation.