The Japanese word Sosai (Japanese:総裁, "Sōsai") means roughly "president" or "director-general". It is used in several ways:

This office also exist in various sports, in particular budō, business and charitable organizations. The term is also used to translate the head of various foreign organizations.

The most famous of such people is Sōsai Ōyama Masutatsu, who earned this appellation by creating a karate style called Kyokushinkai and spreading karate in the western world.

Mas Oyama is to be called "Sosai" because of his contributions especially in the world of Martial Arts and in the overall history of Japan.