Hisen (飛仙, Flying Sage) is a kind of Sennin which does not serve a ruler. They are listed upon the Divine Registry of a kingdom, though they are not required to serve a kingdom's ruler in anyway in contrast to Grounded Sages.
A individual can become a hisen after being granted the status by a kingdom's ruler, such as Lady Riyou of the Bluemist Aerie in Sai. In contrast, all the sages and oracles who serve on the Five Mountains ascend to sagehood on their own power and achievements. These sages are also accorded the rank of "Count" and have sufficient rank and power to cross the Void Sea.