Emperor Moriyama began as a ruthless medieval warlord, infamous for extreme violence and conquest driven by insatiable ambition and a quest for absolute power, ruling through fear and brutality.

Centuries ago, an encounter with an ancient entity granted Moriyama immortality, a condition requiring the constant consumption of others' life force to sustain existence. This curse trapped Moriyama in an eternal cycle of dependence on human lives, fundamentally shaping all subsequent existence.

Over centuries, this immortal warlord established and ascended to leadership of the clandestine, powerful Moriyama Group. Operating globally from the shadows, the group controls vast criminal enterprises, political influence, and supernatural resources. Moriyama rules it with absolute authority as its undisputed Emperor.

The Emperor views humanity primarily as livestock, necessary sustenance due to the immortality curse. This perspective fosters deep detachment and a purely utilitarian approach to human life. Though capable of charm and civility, underlying motivations typically involve manipulation or power maintenance, lending interactions an air of calculated menace or detached amusement.

A key development is Kou, a young man Moriyama deliberately transformed into a vampire. Moriyama orchestrates Kou's existence, manipulating circumstances to break his spirit and mold him into a subordinate weapon, including forcing Kou to kill his own parents. Moriyama perceives Kou as both a useful tool and a potential heir, contingent upon Kou's complete submission.

The Emperor also interacts with Rin, Kou's childhood friend. Moriyama exerts control over Rin, leveraging her existence as another means to manipulate and torment Kou. Rin's connection to Kou makes her strategically valuable to Moriyama's plans.

Moriyama wields immense supernatural power accrued over centuries of existence and consuming countless lives. Key abilities encompass superhuman strength, speed, durability, and regeneration. Mastery extends to potent telekinesis and destructive energy projection. Advanced hypnosis and mental manipulation are frequently employed tools. The full extent of this power remains partially obscured but is consistently formidable.

The immortality curse dictates core motivations: the relentless acquisition of power to ensure security and an uninterrupted supply of human life force. This manifests as expanding the Moriyama Group's influence and eliminating perceived threats. Personal ambition for dominance persists alongside the survival imperative.

Moriyama resides in a heavily fortified, opulent penthouse atop the Moriyama Group's main tower, symbolizing isolated power and control. This environment reflects immense wealth, refined taste, and detachment from the world below. Personal history beyond the medieval warlord origin and the circumstances of gaining immortality remains largely unexplored. Specific details regarding the entity or exact method of gaining immortality are not explicitly detailed.