Miya-san, Miya-san (宮さん宮さん) - Boshin War Song

Lyrics by Viscount Yajirō Shinagawa, In which the song became popular among Royalists during the Boshin War. It is about the man asking a member of the Imperial Family (宮) about the flag that is leading the file. He then later answered that it is the Imperial Standard (錦の御旗), the banner of the Imperial court army. It was customary in Japan that an emperor bestowed it on his military commanders as proof of putting down the emperor's enemy. 一天万乗 directly translate as heaven's ten thousand chariot lord or divine emperor of the realm. The term of "ten thousand chariots" could tract its form in China as a means to show the power of the emperor. It could also mean "Emperor of the Realm" rather than "Emperor of the World".

Azuma (東) could mean simply "East" in an archaic term.

Translation with the help of various comments, wikinatory, and google translate.