Tsukasa Kenmochi operates as a powerful onmyoji while maintaining the professional cover of an acupuncturist. He bears the moniker "The Dark Deathkeeper," signifying his pursuit of those who exploit supernatural powers. A secret descendant of Abe no Seimei, Kenmochi wields specialized magical needles called *amagihagiri* as his primary weapons for both combat and exorcism.

His background includes mentoring Chikae Ikeda, a spiritually adept and martially trained student he encountered while investigating a curse-related murder in Nara. This mentorship cements Kenmochi's role as the knowledgeable figure within his team. He maintains a perpetually calm and stoic demeanor, serving as the tactical expert during confrontations with supernatural entities.

Kenmochi develops a rivalry with Hiroe Ikeda, Chikae's half-brother, following Hiroe's involvement in a conspiracy targeting their family. Operating under the alias "Dragon King," Hiroe occasionally allies with Kenmochi's group but clashes with him due to conflicting methods or objectives. Despite his reserved nature, Kenmochi integrates into the team dynamic alongside government agent Nishikiori and the Ōgi sisters, functioning as a strategic counterpart to their spiritual abilities.