二十日鼠 はつかねずみ Also written ハツカネズミ, 廿日鼠 Meanings Noun house mouse (Mus musculus) Kanji 二 two 十 ten 日 day 鼠 rat; mouse; dark gray. Read as ねずみ. Words containing 二十日鼠 二十日鼠と人間 (はつかねずみとにんげん) Of Mice and Men (1937 novella by John Steinbeck) Jinuma: Japanese Dictionary · Word lists