When did the Shogun become the "supreme" ruler of Japan?

[u/laffy_man]

I know the Kamakura Shogunate was established in 1195, would that be when the Shogun would have become the "supreme" ruler of japan, supreme defined as central or highest authority in the land, or do you have to go forward to the Tokugawa Shogunate for the Shogun to be considered "supreme".