Kurohagane (黒鋼 meaning Black Steel) is a robotic ninja created by the Nakatomi conglomerate who ordered him to work with Jimushi and retrieve pieces of Akujiki and he is the main antagonist of the 2003 videogame Nightshade. Although a soulless robot, he has his own agenda.
In his first appearance, Kurohagane appears as a tall armored ninja adorned in black, purple and red. His most defining feature is his helmet which features two long horns extending from either side of his head and a single gray horn protruding upward from the right side. His "face" is covered in a transparent mask with the kanji of Mu (無; Nothingness, Emptiness) superimposed on it.
After being upgraded, his appearance remains the same, but now wears heavy armor and a cluster of glowing thrusters strapped to his back as well as a wrist-mounted multi-purpose weapon on his left arm.
Upon absorbing Akujiki into himself, he sheds his armor and takes on a distinct human form resembling Hotsuma, wearing a black version of his trademark scarf
Kurohagane as a cyborg shinobi possesses incredible speed, durability, tolerance to pain and enhanced physical strength, though not on par with Hibana. His further enhancements by Nakatomi equipped him with a series of thrusters on his back and legs to give him a powerful dash to slip behind his target's defenses or travel vast distances at high speeds. The heavy armor on his body also gave him a much greater defense and a multi-purpose weapon was installed to increase his attack options, which include an energy sword and a machine gun. The arm itself could now detach and act as a rocket to attack opponents from afar.
After absorbing Akujiki, Kurohagane's style changes completely to that of the sword's previous wielder, Hotsuma. Forgoing the use of technology, he relies solely on Akujiki's dark power and mimics Hotsuma's techniques, to the point of using a Tate version of his Stealth Dash. If left alone, he will absorb the images into himself to perform a far more lethal version of Hotsuma's Special Attack. He also has a darker version of the Raijin spell that forms a purple barrier that repels and damages those who attack him directly.
Kurohagane was manufactured by the Nakatomi Conglomerate to help Jimushi retrieve the pieces of Akujiki, which had been shattered and scattered across Tokyo thanks to the efforts of Kagari Ubusuna and Hotsuma. As seen in the intro, Kurohagane apparently had in possession of one of the fragments before the game starts. He is later deployed in order to terminate his rival's agent, Hibana, a descendant of the Oboro Clan who originally held Akujiki. However, he was easily defeated and left to be scrapped after being sliced across his body and the jet he was riding crashed.
Nakatomi managed to retrieve his body and upgraded it in a future preparation with Hibana. In the meantime, he was enlisted into Nakatomi's shinobi mercenary group to help them retrieve more pieces of Akujiki. He also seems to have developed a limited form of speech and encounters the female ninja when she escaped one of Nakatomi's recently destroyed facilities. Despite the improved performance and additional weaponry, he is still bested in battle. He tries to reach out to Hibana, but is then suddenly impaled on a blade from the ground. The weapon was from none other than Jimushi himself. Still functional, he tosses his Akujiki shard to his former partner but is then destroyed by his other subordinate, Hisui.
Thought to be dead, Kurohagane later makes a surprise return and snatches away the Akujiki pieces in Jimushi's possession when he tried to give them to her after revealing his true intentions. He tries to shoot down Hibana, but Jimushi jumps in the way, sacrificing himself to save her.
In the game's closing segments, Kurohagane appears before Hibana at the Golden Castle and steals the final piece of Akujiki, restoring the blade to its original form. He now displays full sentience and a will of his own and desires for Hibana to take up Akujiki with him as her subordinate. When Hibana declines, he instead motions to kill her with Akujiki and uses its power to transform into a twisted visage of the weapon's previous wielder and final leader of the Oboro: Hotsuma. Despite the overwhelming power granted by the evil blade, he is felled one more time by Hibana. His body falls to its knees and lies motionless, Hibana taking the sword from him.
- Kurohagane shares the same voice actor as Moritsune from Shinobi in English.
- If you pause in between some of his Akujiki powered Ninjutsu, you'll hear him say the full sentence to his attack "This is Akujiki's true power! Light of Fury!"
- Kurohagane α makes his appearance in Project X Zone 2, and gives Hotsuma an uneasy feeling.
- Kurohagane was programmed with the battle data of the Oboro Clan, enabling him to learn even Hotsuma and Moritsune's attacks.