Every human, otherworldly being, or strange entity that exists in the world, upon awakening to their own nature and understanding of themselves and the world, can cultivate their body to possess the ability of a "Self Noumenon." The characters in the story primarily include:

Monster Investigators, who regularly investigate humans, supernaturals, and monsters that have cultivated their "Self Noumenon." They observe their states of existence in the world, maintain balance among different beings, stop law-breaking Self Noumenons and monsters, and report on the abilities of various Self Noumenon cultivators. Through this, a variety of strange and extraordinary adventures are revealed, showcasing human nature through humor, action, sorrow, and exploration in a captivating adventure manga.