Japanese squirrels belong to tree squirrels which means they live in trees. They have bushy tails, large tufted ears, and sharp claws. Their fur color changes depending on the season. In summer, it is red-orange and in winter the fur becomes gray or light-brown and white under the chin and on the belly.
Japanese squirrels are native to Japan. Their range includes the islands of Honshū, Shikoku, and Kyushu. Japanese squirrels inhabit lowland to subalpine mixed-species forests and pine forests.
Japanese squirrels are diurnal creatures. They are usually active in the early morning, and during the day they like to sleep in a tree. They live in nests which they build in trees and then switch between them. These squirrels don't hebirnate. To prepare for the winter they store nuts and seeds in their caches. Sometimes they forget locations of the caches they made and may found caches of a different squirrel which they don't hesitate to steal. Japanese squirrels are generally solitary, but during the winter adults may nest together. There is a social hierarchy among males and females; older and heavier individuals are usually more dominant and have larger home ranges.
Japanese squirrels breed from February to March and May to June. Females give birth to 2-6 kittens. The gestation period usually lasts around 39-40 days. Females nurse their young until they reach 62 days of age. Females reach reproductive maturity at around 296 days old and males at 320 days old.
One of the factors affecting the local extinction of Japanese squirrels in Kyushu island is forest fragmentation by humans.
The IUCN Red List and other sources do not provide the Japanese squirrel total population size. This animal is common throughout its known range. Currently this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.