Oki is based on the Ainu hero Okikurumi. He is credited with teaching the Ainu, the native people of Hokkaido, the northern island of Japan, with the arts of hunting and fishing. He is the main hero of many oina, epic poems, and thus was also known as Oinakamui (god of oina). Furthermore, he is the son of the goddess of elm trees, which were commonly used by the Ainu for fire, and so Okikurumi is associated with fire as well. This is probably reflected in Oki’s hot temperament and fiery personality (and hair). And when he became an adult, his mother gave him a sword–which, when he took it, burst into flame and destroyed the dark beings around it. The sword was called kutoneshirika. (The only further information I’ve found is in Japanese I can’t quite read.)
As it happens, it seems that Yoshitsune (Ushiwaka) and Benkei went to Hokkaido, and they taught the Ainu how to hunt, fish, and do other useful things. Yoshitsune was called Okikurumi, and Benkei was called Samai un guru, which literally means “Japanese person”. Samickle’s Japanese name is Samaikuru. Coincidence? I think not.
Okikurumi faces a wind spirit.
Anyway, maybe this is a reason behind the constant Oki-Waka dilemma!
Bonus picture: cool Ainu robe