An O.P.T. or O-Part Tactician, are people who are able to and make use of O-Parts. Not everyone can utilise O-Parts except OPTs who can expel Spirit when they manage O-Parts. OPTs are not the original inhabitants of the land but are space travelers from a different planet. The chance of being an OPT is actually very rare as there is only a one in twenty thousand chance of being one. And OPTs only make up .005% of the population in the world.