Ki

Ki (氣) is an energy given off by people and objects when they move. It exists separate from mana.

Overview
Ki as a principle originates from the Black Bull's Captain Yami's homeland. With proper training it can be used to predict attacks and others' movements, including natural objects and events found in nature. It can also be used to detect whether someone is lying. Each individual's ki is unique, and it is rare for different individuals' Ki to be the same.