だい日本 にっぽん帝国 ていこく陸軍 りくぐんでしょう
dainipponteikokuri kugundeshō

Noun
Desu Copula

Expresses probability in a polite manner ("probably…") of 大日本帝国陸軍

1. Probably the Imperial Japanese Army.

Polite
Presumptive
Conjecture