Kurogane is serious and extremely perceptive, being able to quickly discern Syaoran’s fighting ability (along with Syaoran’s blind right eye) as well as Fai D. Flourite’s true nature and fighting capabilities. While he seems rather irreverent, he is also very loyal. He is likely the most experienced fighter in the group and wiser than he appears. He becomes Syaoran’s sword fighting teacher, presenting the boy with the same philosophy he believes in: a sword is used to cut only when needed and not used to cut anything if it is not necessary. While serious, Kurogane is very easily irked by others, especially by Mokona Modoki and Fai, who keep calling him ridiculously cutesy nicknames such as “Kuro-puu”, “Kuro-wan-wan” or “Kuro-rin”. However abrasive and ruthless Kurogane may seem, he has a compassionate nature and a desire to protect. An example of this would be how Kurogane continually questions Fai on his actions and character, and lets the wizard know that he should stop hanging onto his past and embrace the future with his new companions. Or, Kurogane’s own statement that “If someone wants to take away the ones I want to protect, I’ll kill them too”.
His compassion and protective nature is especially clear when his actions early in the series are compared to his actions later on. He had straight out told Syaoran in their first world, the Hanshin Republic, that the quest has nothing at all to do with him. In the next world they visit (Koryo Country) however, Kurogane offers his services to help raid the castle of an evil lord, and stays behind in battle to let Syaoran go on ahead. Eventually, he risks a loss in strength to avenge his comrades’ “death” (they were of course still alive) by defeating their killer in battle. It is noted that after he finds out Fai and Syaoran are still alive, he lost his passion for the battle.
He obtained a new sword in Outo called the Souhi (Blue Ice or Pale Ice) and taught Syaoran the skills of sword fighting and sensing attacks from the left.
In Horitsuba Gakuen, he is the PE teacher.
At the beginning of the story, Kurogane told Syaoran that he would not help in finding Sakura’s feathers, since it was not related to him. However, he ended up aiding Syaoran and the others anyway, teaching Syaoran how to fight and use a sword as well.
In the Tokyo arc, Kurogane was involved in a short fight with Kamui. Later, he wished to Yuuko to save Fai’s life, after Fai’s eye was ripped out by the clone Syaoran. Through an arrangement by Yuuko, Kurogane and Kamui mixed their blood and forced Fai to drink it. Fai thus became a vampire and survived. Since it was not Fai’s wish to live but Kurogane’s, Fai can only take blood from Kurogane. Fai painfully refrained from calling Kurogane nicknames from then on, in an effort to distance himself from Kurogane.
Kurogane noticed that Fai and Sakura were up to something in the Infinity world, but did not say anything. After Sakura left, however, he finally spoke up, refusing to let Fai give up his eyesight to go to Celes. Kurogane told Yuuko they would all pay a fourth of the price to go save Sakura’s body from Celes.
In the latter parts of Volume 20, Ashura used his magic to show Syaoran, Kurogane, and Mokona visions of Fai’s tragic past. This caused an angry and betrayed Kurogane to unsheathe his sword and attack Ashura and Fai. He and Fai fought a fierce battle that devastated the room around them. In the mayhem, Kurogane destroyed the body of Fai’s twin and managed to overpower Fai in that moment of weakness, saying to the overpowered Fai something along the lines of “I thought I already told you I don’t have anything to do with your past”. Kurogane then turned on Ashura, demanding to know why he’d shown them Fai’s memories. The king responded by saying that he only wanted Fai to “grant his wish” and kill him. Ashura then launched vicious spells against Fai, Kurogane, Syaoran, Mokona, and a defenseless Sakura’s body in order to force Fai’s hand. In the chaos that followed, one of the massive ice stagamites that he conjured pierced Kurogane through his lower right side.
Korogane is then apparently spared the damage due to the protective spell that placed upon him before leaving Japan by Tomoyo. He then stabs King Ashura, and after the King’s death the group is seen possibly leaving for the next world.
Fai’s second curse caused him to suck up the world of Ceres; Fai tries to transport Kurogane and the others out of the small sphere that Ceres has become, but he doesn’t have enough magic to do so. He only succeeds in transporting Syaoran, Sakura, and Mokona. Then Mokona’s earring (a magical tool made by Yuuko) was able to drill a hole into the sphere, but only one person could pass through. When Fai told Kurogane to leave him, Kurogane cut off his left arm and left it and Souhi as a sacrifice and rescued Fai.
In chapter 167, Kurogane wakes up and finds himself back in his country, with Princess Tomoyo by his bed. Tomoyo welcomes Kurogane home and asks him if he has found out the true meaning of strength, to which he replies that he doesn’t know. However, he explains to Tomoyo that he doesn’t regret giving up his arm to take Fai with him, and tells her that he knows that some things can’t be protected only by (physical) strength. This surprises Tomoyo, but she acknowledges that Kurogane has definitely realized the true meaning of strength. She then lets Fai into Kurogane’s room. Kurogane seems genuinely pleased to see Fai, while Fai doesn’t express much emotion, until suddenly he punches Kurogane. Kurogane doesn’t quite react to this, far too startled. Fai then smiles at him, saying “This is payback, Kuro-sama.” The smile seems like the real thing, and Fai has gone back to using suffixes on Kurogane’s name. Kurogane grins back, promising to beat Fai up for that.
In chapter 169, Kurogane is approached by Fuuma who has come to Nihon Country with an artificial arm from Piffle Country, however Kurogane refuses the arm by saying that he “will not pay anything to that witch for it.” Fai replies by saying that he had agreed to pay the price while he slept, and gives up the last of his magic. In the second to last page of 169, Kurogane is seen with the arm attached, but claims that it “feels weird.”