In the not-too-distant future, Shinjuku,Tokyo is under siege by strange demons-turned-machines led by a sinister ex-hero named Eko. Though the future looks bleak, all is not lost. There is a young hero chosen by the Landlord Yurine to fight against the phantoms that plague Japan. He is KARAS, a powerful armored being appointed to defend the innocent. With the help of Yurine, his mystical mentor, Karas sets out to preserve the natural balance of the universe, and to prevent the friendly old-world monsters from being transformed into mechanical demons! A man by the name of Otaha a former Yakuza clansman living in Shinjuku (less distant future) populated only by humans and Yokai (spritis/oni based on japanese mythology). A secret war is raging between the renegade ex-karas warrior Eko and a spectral warrior known as the Karas. Eko has mechanized himself and his followers to defend against the unearthly fury of the Karas; in addition to an armored humanoid form, the Karas can transform into any of various heavily armed and armored vehicles. Eko and his followers prefer to live in the material realm in human form, but to continue doing so they must feed on the fluids of human bodies. Their periodic feasts result in massacres that leave only a single traumatized survivor; these "inexplicable" tragedies are the obsession of a marginalized police inspector whose daughter was the survivor of one such massacre. Opposing Eko are the renegade demon Nue, who also lives in the material world in human form but refuses to drink blood or take a mechanized form, and Otoha, a former human who is summoned by the mysterious Yurine to become the new Karas. Otoha the recent Raven Karas is trying to seek great vengeance against the yakuza clansman that slaugtered his brother and nearly killed him as well protect the city from the evil forces of eko and his minions.
Karas are "heard" by Yurine, the physical embodiment of hope in different cities of japan chose karas by people who are on or near the verge of death and who know extreme sorrow. That person are then transported to the spiritual world where they are given a "item" that gives them the information about yurine, karas's duties, the place that he is in now, ect. The raven karas, neither human nor mystical entity is set to protect the cities of japan from mikura,
demons, bent on draining the blood of humans and posssibly beyond, in hopes that Eko may be able to take over the cities. There are different Karas warriors in different cities by different yurines. In order to fight and (out)match mikura, they have combined their spirit vanquishing magics with "Technology" in order to fight mikura. Different Karas represent different paths for the good of the city.
The suit in which the user's sole is transported into has many vast capabilities in order to combat mikura or even rouge Karas' such as Eko. When using the armor, the wearer is granted vast speed, agility, strength, durability, and enhanced senses. The armor is polymorphic and can take on two additional forms: a Jet and a Car, both of these are fitted with offensive arsenal that a traditional aerial or ground combat vehicle commonly have such as missles or turrets that fire bolts of energy . The artilliery refined into the bipedal armor include explosive shruikens and a katana that can be mentally controlled to move when not in the users grasp. The armor also conceals a versatile chain used in situations like guiding karas through turns when traversing at high speeds. Unbeknownst to humans, when a fight occurs between a Karas and his or hers opponent they are rendered invisible to be concealed from human awareness. Karas can also tap into an alternate power, a "rage mode" if you will, that further increases all of the user's abilities.
Yurine are the physical/spiritual manifestations of hope within a city, each Yurine represents a different city. Different Yurines are observed on what color hair they have and what clothing they wear. A Yurine, although powerful is vulnerable, such as when Tsuchigumo kidnapped Yurine and Otoha transformed back into a human, this shows that a Yurine has much jurisdiction over whether or not a karas can transform or access his/her full potential, as when another karas tried to unsheath her sword and failed. A Yurine can also shapeshift into a cat, usually for the purpose of observing potential karas warriors.