あれちねずみじゃありませんでした
荒地鼠じゃありませんでした
arechinezumijārimasendeshita

Noun
Desu Copula

The polite, past negative form of あれちねずみ

1. Was not a field mouse.; Was not a vole.

Past/Perfective
Negative
Polite
Terminal Form
Usually Written in Kana