The adult animal is about 10 centimeters from its nose to the tip of the tail, and weighs 20 to 30 grams except in winter when it gains 10 more grams to go into hibernation. You can distinguish the species from other types of mice by a black line on the back. In kanji, Yamane is described as 山鼠 (mountain mouse) or 冬眠鼠 (hibernating mouse).

It is a precious and mysterious wild animal, called differently in different places in the country with 13 names including Momotori, Risu-nezumi, Kori-nezumi and so on(Yutaka Nishimura (2011) The Day I Met Yamane).

Yamane is also called living fossil or forest fairy, as it inhabits Japan for approximately 5.1 million years (4.2 to 6.2 million years).

Known for its exceptionally long hibernation, it appears in the Alice in Wonderland as a strange mouse always sleeping. Actually, it spends half of a day sleeping and half of a year hibernating, which makes it conceived to be the most unique animal in Japan.

Yamane lives in forests, where it moves branch to branch at night, and build a nest in a hole of a tree with moss or pieces of bark. It eats insects, nuts, etc. and remains dormant over winter with remarkably decreased body heat unlike a bear, which just sleeps without diapause.

We named our company Yamane-shuzo, hoping to contribute to preserving and passing on the rich natural environment where it can survive to future generations.