The Eagle Undead is the Category Jack of Spades, a member of the elite Royal Club Undead in Kamen Rider Blade. In his human guise he presents himself as a man named Takahara, a name that is sometimes rendered as Kougen in certain translations. He is a sophisticated, bespectacled figure who favors suits, carrying an air of quiet intelligence and calm composure. Beneath that polished exterior lies an ancient warrior bound by a solemn pact forged ten thousand years earlier during the previous Battle Fight, a pact that defines his entire existence.

His background is rooted in the distant past, when he and the Mantis Undead, who would later lend his form to Kamen Rider Chalice, agreed that they would fight until only the two of them remained. To the Eagle Undead, this promise is sacrosanct, a bond of honor that transcends the millennia and gives his participation in the revived Battle Fight a deeply personal dimension. He is motivated not by a desire for conquest or destruction but by a fierce loyalty to his old comrade and a need to see their shared destiny through to its proper end.

When the Eagle Undead resurfaces in the modern day, he witnesses Hajime Aikawa transform into Kamen Rider Chalice. Mistakenly believing that Hajime has sealed the true Mantis Undead and stolen his form, the Eagle Undead’s mission shifts toward reclaiming the Change Mantis card and avenging what he perceives as a grievous wrong. This misidentification drives his actions across two episodes. He intercepts Hajime, snatches the Change Mantis card right out of his hand, and later kidnaps the photographer Kamioka to pressure Hajime into revealing his true identity. Throughout these encounters he clashes with both Hajime and Kazuma Kenzaki, the user of Kamen Rider Blade, seeing them as obstacles to be removed in the name of loyalty.

The Eagle Undead’s relationship with the Mantis Undead is the cornerstone of his character. He treats the memory of his ally as something sacred and reacts with open hostility toward anyone he believes has desecrated it. He also briefly interacts with the Orchid Undead, who warns him not to interfere in her own schemes. These connections reveal a figure who operates with a clear, if misguided, sense of purpose in a world where other Undead are far more manipulative or indifferent.

His role in the story is that of a catalyst. By forcing Hajime to confront the fact that he is using the power of a sealed Undead, the Eagle Undead pushes Hajime to reflect on his own nature as the Joker and on the humanity he has begun to value. While the Eagle Undead himself remains antagonistic, his actions inadvertently nudge the larger narrative forward, highlighting the tangled legacy of the Battle Fight and the weight of ancient promises.

The Eagle Undead’s arc is short but complete. When he finally learns that Hajime is not the Mantis Undead but the Joker, he acknowledges his error, his long-cherished understanding of his pact crumbling in an instant. He accepts the truth before being sealed, and it is Kamen Rider Blade who delivers the finishing blow, using the Lightning Sonic finisher to capture him within a Rouse Card. In that moment, the Eagle Undead is granted a kind of closure, his loyalty ultimately answered with the realization that the real Mantis Undead had already been sealed long ago.

In terms of abilities, his signature traits are tied to his avian nature. As an Undead he can fly at high speeds and possesses sharp vision suited for tracking targets over vast distances. In combat he generates feather-shaped projectiles that he hurls like throwing daggers, a ranged attack that keeps opponents off balance until he closes in with the large claws on his arms. His human form, while lacking any overt supernatural powers, remains the vessel through which he plans, negotiates, and pursues his personal code of honor until the final confrontation.