Jasei is a wizard who claims to have 'mastered the art of magic'. His human body was destroyed during a magical experiment, but he lives on in a state reminiscent of lichdom, with a large gem in what would have been his abdomen apparently sustaining his existence on Earth. Jasei powers his unnatural existence by feeding on despair. He is powerful and cunning, willing to concoct schemes which may take years to come to fruition, in order to reap the greatest possible amount of despair for his personal enjoyment. One example of this was his raising and tutoring Kaoru Kawahira to be a good and kind person, after having placed the boy's soul in a counterfeit body, all with the eventual goal of revealing the depth of his own evil, sadism and treachery so Kaoru's heart and spirit would be broken. Jasei is an even more powerful wizard than Sekidōsai, as he proved capable of hoodwinking the latter without his even noticing, and wields enough power to overwhelm most of the Inukami and Yoko combined.