He is a black cat with two tails, which is considered to be sacred in ancient Japan. The lower half of his face is covered with chocolate-brown fur, which slopes upward between his eyes, while his chest fur is white. There is a ring of white fur on his upper right leg. He has large, greenish-yellow eyes with green irises, as well as small horns on his head. When Kuro goes into his nekomata form, he becomes enormous, easily towering over human adults.
As a cat, he is very playful and energetic, as he is constantly seen around Rin, asking him to play with him. However, he does have a fierce side, as shown when he attacked the humans bulldozing his shrine. He loves Shiro's catnip wine. He generally sleeps on Rin's back. He does not like being lonely and is seen shedding tears when he comes to accept the fact of Shiro's death.
In ancient times, Kuro lived peacefully with humans as the protective deity for local silkworm farmers. In exchange for protecting the silkworms from being killed by mice and other disasters, he received offerings of food, as well as festivals in his name.
However, as times changed and silk cultivation became outdated, people stopped worshipping Kuro. Eventually, they even bulldozed his shrine and develop the land it once stood on. Because of this, Kuro became enraged and attacked the humans for their actions. The locals turned to the True Cross Academy, who sent a team of Exorcists, led by Shiro Fujimoto, to stop him. Shiro calmed down Kuro by talking to him, sharing catnip wine, and making an offer for the cat to become his familiar. He soon gained a new role as one of the guardians of the True Cross Academy.
True Cross Academy arc
Kuro is guarding the Southern Rear Entrance of the True Cross Academy, as usual, when he overhears one of the guards mention Shiro's death while waiting for his master. Kuro reacts violently and begins to attack everyone while denying the news of his master's death as "lies." Yukio and Rin arrive at the scene, and Yukio reveals that Shiro left a "poison" that would bring Kuro down in the event of his untimely death. Meanwhile, Rin learns that he can hear Kuro's inner thoughts.
When Rin realizes that Kuro is simply lonely and does not want to accept Shiro's death, he stops Yukio from using the "poison" against Kuro and convinces him to give Rin a chance to reason with Kuro. Rin confronts Kuro and tells him that Shiro is dead and that he truly understands his feelings of grief. Kuro sees Shiro in Rin and finally comes to accept that Shiro has died, causing him to cry in agony. After that incident, Kuro grows close to Rin and becomes his own familiar. He stays with him and Yukio, usually at their dorm when they have a mission or school. The "poison" that Shiro gave Yukio was not poison at all, it was his famous catnip wine which at the end Kuro recognizes the smell and drinks it; he ends up getting drunk after finishing it.
Training Camp arc
Kuro accompanies a restless Rin to the top of a tower on the academy's grounds. After spending some time contemplating Shura's words. Rin asks Kuro if he would like to play. Kuro is all too happy to oblige and quickly changes into his nekomata form and then begins to play-fight with Rin.
Impure King Revival arc
Kuro accompanies Rin and the other Exwires on the trip to Kyoto. Later, while the Impure King is starting to take on the shape of a building within the forest, Kuro comes to Rin and Ryuji Suguro, warning them that the area is too dangerous and they should turn back. Rin refuses, saying that if he does not do something about the Impure King soon, things would get even worse. Kuro reluctantly transforms into his nekomata form and tells Rin that he will take him and Ryuji closer to the Impure King.
Rin and Ryuji ride on Kuro's back where he can climb on the building. During this, Rin pretends to be a knight with Kuro as his "horse" and Ryuji as a "princess" (who appears to be scared of riding Kuro and of the Impure King). Kuro can detect ground nearby that is untouched by the Impure King for Ryuji to chant his spell and put a barrier over. Ryuji can do the spell but he, Rin, and Kuro are attacked by the spores of the Impure King.
Terror of the Kraken arc
True Cross Academy Festival arc
Kuro is seen heading out with Rin to go on the mission.
Powers & Abilities
Kuro can change from a small cat into a nekomata, a giant Demon cat, at any time. With this change, Kuro grows to an enormous size and gains immense strength and power. His strength is so great that he can topple bulldozers and other construction equipment easily. He is also said to have a very good sense of hearing.
Kuro also has Demon telepathy and can mentally communicate with other Demons.
- Kuro (黒) means "black", which is the reason why he is referred to in the English Sub as "Blacky" or "Blackie".
- From chapters 8 to 13, Kuro was first seen with his left fang curved up over his mouth in both his smaller and nekomata forms. However, in the anime and chapters 17 and 28, his fang was shown not to be curved at all in either of his forms.
- It is shown in an anime-exclusive filler episode that if Kuro, like all cats, eats raw squid, he gets sick and cannot stand for a certain period.
- He generally sleeps on Rin's back.
- (To members of the True Cross Order) "Liars! He'd never die! Shiro's the greatest... He'll come back home! I don't believe you! He's coming back! Until then, I can't die either!"