はつかねずみでしょう
二十日鼠でしょう
hatsukanezumideshō

Noun
Desu Copula

Expresses probability in a polite manner ("probably…") of はつかねずみ

1. Probably the 20th.; Probably a mouse on the 20th.

Polite
Presumptive
Conjecture
Usually Written in Kana