Hiromi Ikeda is the half-brother of Chikae Ikeda and the son of an assemblyman murdered by a supernatural curse. He participated in the conspiracy that killed their father and targeted their mother for personal reasons. After these events, he defected from the conspirators to pursue his own path. He assumes the masked identity "Dragon King" (辰王, shinno), reflecting his proficiency in magical arts and independent agenda.

Operating as Dragon King, he occasionally assists the main exorcist team, particularly against supernatural threats, though his alliance remains sporadic and conditional. His relationship with the team involves fluctuating cooperation, not permanent membership. A notable rivalry exists between him and Tsukasa Kenmochi, an onmyoji descended from Abe no Seimei, stemming from conflicting methodologies and personal tensions rooted in their magical backgrounds and objectives.

Hiromi Ikeda's actions are fueled by personal motivations and unresolved familial conflicts, specifically his father's murder and the conspiracy that engulfed his family. His background as a magic user and adoption of the Dragon King persona emphasize his detachment from conventional alliances and focus on autonomous goals.