Omusha

Omusha (オムシャ), also umusa or umsa, was an Ainu greeting ritual that, like the related uimamu (ウイマム), became a ceremonial—of trade—full of the political symbolism of subservience, to the Matsumae Domain.

Name
The word is understood to derive from the Ainu u (ウ), referring to mutuality, and musa (ムシャ), translated and defined by John Batchelor as "to stroke the head in salutation".