上代 じょうだい特殊 とくしゅ仮名遣 かなずかいでしょう
jōdaitokushukana zukaideshō

Noun
Desu Copula

Expresses probability in a polite manner ("probably…") of 上代特殊仮名遣い

1. Probably archaic kana usage.; Probably Old Japanese kana orthography.

Polite
Presumptive
Conjecture
Linguistics