Beings of any species can wield ki energy, the life force that flows through all things. Though the ease of learning varies. Mortals, especially humans, seem to have a harder time breaking through than yokai. This is because humans aren't born with an open ki well nor can they see the energy's course.
How do they 'do magic'?
Reactions to MagicIn the last 20-30 years, there's been an increase in demand for services such as magical healing, protection—especially for more powerful charms, and portals. Most requestors and customers are yokai.
Keep in mind, that ki use isn't common for mortals. If someone sees a ki user performing 'magic', they will receive reactions of either fear or fascination. In the case of fear, they may be shunned. With fascination, the ki user will receive non-stop requests for the spells observed. In the few cases ki users have gone abroad, they were well received and setup businesses around their magical services.