上代 じょうだい東国 とうごく方言 ほうげんでしょう
jōdaito ugoku hōgendeshō

Noun
Desu Copula

Expresses probability in a polite manner ("probably…") of 上代東国方言

1. Probably an archaic Tōkai dialect.

Polite
Presumptive
Conjecture
Linguistics