The rank was only ever held by the Emperor of Japan as Supreme commander-in-chief of the Imperial Japanese Armed Forces and, separately, the highest-ranking officer in each of the military branches.
The term originated in the Chinese military title da yuan shuai (大元帥), a title higher than yuan shuai (元帥, pronounced gensui in Japanese).
142" of the Constitution of the Empire of Japan (Chapter 1 Part 1) of 30 September 1889, the Emperor was officially given the rank of dai-gensui and installed as supreme commander of the Army and Navy.
The kanji characters also refer to a Buddhist deity, Daigensui Myō'ō (大元帥明王), a Wisdom King worshipped by the Imperial Court since Emperor Ninmyō and by the Shingon sect, for its legendary miraculous power to quell foreign enemies and rebellions, just like a military leader.
The insignia of a dai-gensui were identical to those of a full general, with the addition of the gold imperial chrysanthemum.