Train Heartnet (トレイン＝ハートネット Torein Hātonetto) is the one of the four primary protagonists in the anime and manga Black Cat. In the beginning of both the manga and the anime Train is a ruthless assassin hired by the organization known as Chronos. He is given the number XIII by Chronos because he is the "bringer of bad luck", hence his nickname being the Black Cat. In the very beginning of the anime, and a little ways into the manga Train meets a woman by the name of Saya Minatsuki. After this fateful meeting Train begins to learn the ways of what he calls the "stray cat" (i.e. do what you want, as you want). After what seems like a few days of knowing Saya he quits Chronos and goes about on his own. After his change of heart, he works as a sweeper alongside Sven Vollfied and Eve. He is never seen without his cat collar (a red ribbon with a golden bell hanging from it) around his neck, which was fashioned for him by Eve after their meeting (only in the anime). After leaving Chronos Train never returns, though he does keep his weapon, a gun made of Orihalcum that was given to him by number I of Chronos: Sephiria. For a while he views Chronos as an enemy, but in the anime he asks for their help in the end.
In the manga version of Black Cat, Train Heartnet is a lighthearted, courageous man who's highly skilled with a gun, on a practically supernatural level. He works as a sweeper with his partner Sven. He seems to enjoy tormenting him and tightening their already small budget as low-paid sweepers, as it is shown, for example, by his exaggerated food consumption. Some of Train's distinguishing features are his spikey brown ruffled hair, his catlike slitted eyes, a choker with a tiny bell attached to it, and the XIII tattoo he has on his chest. He has low alcohol tolerance, but loves to drink milk. Contrarily, for some reason unknown, it seems his liking of fish is very minimal. His nickname is "Black Cat", and was given to him when he was still working as an assassin in Chronos. His weapon-of-choice is Hades, an ornate black revolver with a matching XIII engraved into its side. He received this gun when he entered Chronos, and still uses it. He is also skilled at disguises, can sleep anywhere, even inside a cramped porcelain vase, and tends to be clueless about most other important things; for instance, he couldn't remember what he originally looked like after turning into a child and gets bored of reading after the table of contents page in a book. In the past, he was once a bitter, emotionless assassin, but after he met Minatsuki Saya, he began to loosen up and was moved by her freedom as a sweeper. His partner in Chronos, Creed Diskenth, was not pleased by this change in Train, and killed Saya. Train afterwards left Chronos in order to be an independent sweeper in the memory of Saya, and later on joined with Sven Vollfied as his partner. Once Creed appears, Train decides to capture him, not as an assassin seeking revenge, but as a sweeper. Following his incident of being reverted to a child due to Doctor's Lucifer nanomachine, Train becomes able to charge his Hades with his body's cell energy to make a regular bullet much faster and more powerful; enough to actually pierce an alloy plate. Hades is then compared to one of the scientific-research supersonic-speed-shooting guns, no more no less than a "Rail Gun". He also has a few melee moves he uses with Hades, which he uses when he wants to defeat Shiki at Clarken Island, when he realizes that he trusts too much in Tao, so he decides to try to make Shiki realize Tao's not a "Perfect" technique, so he shoots his fourth Rail Gun shot at the air (He only could shoot four per day if he wanted the Rail Gun energy circle to renovate normally), saying that he doesn't even need the Rail Gun to beat Tao. In the final battle, he beats Creed by focusing all of his mental and physical energy into shooting one more Rail Gun shot, in combination with a burst bullet. The resulting shot is so powerful, it shatters Creed's sword, as well as partly destroying Hades. After the defeat of Creed, Train was unable to use the rail gun attack. His own theory on this occurrence was that Saya provided it for him spiritually only in order to defeat Creed.
Eight months later, Sven repaired Hades for Train albeit with some parts not made of Orichalcum, shown in the ending. Although Hades is repaired, Train can no longer use Rail Gun anymore, though in the first place he believed that Rail gun is used to defeat Creed. Having served its purpose, Rail Gun will not be used anymore.
The most notable difference between the anime and the manga is the time and way in which he meets Saya, Sven, Eve and Rinslet. In the manga, Train didn't meet Sven until some time after Saya was killed by Creed. In the anime, though, he has a brief encounter with Sven before he even meets the female sweeper, having assassinated Sven's target, the mobster turned governor Lib Tyrant. They clash again when they both raid Torneo's mansion in order to find Eve, who didn't appear in the manga until Train and Sven had been partners in the sweeper business for two years. Rinslet also appeared at this time under her guise of the blonde Elena, posing as Eve's worried "sister." Once again, she appeared earlier in the anime than she did in the manga, though for much the same reason.
Later, Train receives his bell collar from Eve, instead of acquiring it himself. Eve tells him that according to a book she read, putting a bell on a bad cat will help him behave. He's skeptical at first, but eventually accepts it.
From there, the series progresses much the same, with Train furiously pursuing Creed and his Apostles of the Star. As with the majority of manga-gone-anime, a few characters and even more scenes were missing or were heavily edited; an example was meeting Dr. Tearju Lunatique. Also, one extra episode was added during the Apostles arc, which featured Train meeting a Saya look-alike called Saki in the mountains. He helps her protect a "cursed" baby, despite her being so evasive of his questions and somewhat rude when he means well. He encourages her to help the child find his own future, and leaves with Sven, Eve and Rinslet.
During the final fight with Creed, a unique bullet was given to Train from Sephiria and said that it was specially designed from Orihalcon and would destroy anything at an atomic level. In the anime, after Train was hit with the special nano-tech bullet that reduces him back to child form, he didn't obtain anything special (Railgun etc) and all of his abilities were exactly the same.
When the new Eden arc takes place, Train accompanies Sven on his mission to save Eve, recruiting the Sweepers Alliance and the remaining members of Chronos to help. While inside Eden, he runs into Mason, the mastermind behind the Eden plot and former leader of the Chronos Numbers. Creed appears after a long absence and takes over the battle for them, giving Sven and Train a chance to reach Eve. However, they were separated halfway there by Zagine's "ghost," a hallucination of sorts conjured up by Eden. Zagine/Eden attempts to distract Train from his task of rescuing Eve by tempting him with a second chance of killing his parents' murderer, emptying Hades of all but one bullet and asking him to choose life or death; a choice Zagine had given Train after assassinating his parents. Unfortunately for Eden, Train isn't swayed, and at Sven's plea he shoots the stem of the flower holding Eve, thereby freeing her from Eden's control.
In the end, Train left Sven and Eve to travel the world on his own, fitting his personal "stray cat" lifestyle. Sven explains to Eve that he'll eventually come back, because "stray cat[s] always need a doorstep to curl up on." Train sees the image of Saya one last time walking past him; this could be symbolic of his moving on and letting go of the past completely.
During the end credits when Train is traveling the world, Train walks past most of his friends that he has made since leaving Chronos. Saya is the last person to pass Train, symbolizing his freedom as a "stray cat".
Railgun: In the manga, when Train regains his original self after being transformed into a child by the Lucifer bullet, his DNA undergoes a phenomenal change, and he is able to fire electrically accelerated bullets. This is achieved when the electricity in his body is channeled and stored into the orihalcum of his Hades and accelerates his shots like a rail gun. However, it can only work through Train's one-of-a-kind pistol Hades, as the process is only achieved because it is made of Orichalcum. Train loses his ability to use the Railgun after the battle against Creed, thanks to Hades' self-destruction and the loss of the electric currents in his body.
Burst Railgun: Basically, the Burst Railgun is exactly the same as the normal Railgun, except it combines the electrical discharge with one of Sven's custom made "burst bullets," thereby increasing the power. Train uses this ability only once in order to defeat Creed. This attack also destroys Hades, although it is uspecified whether it was the fact that it was in combination with a burst bullet or because it was Train's fifth railgun that day (Train can only use the railgun four times a day or else the power won't recharge).
Black Crow/Claw: Train fires multiple of bullets instantly to speed up a spinning slash that results in a cat's three clawed slash. He uses this ability multiple times during the final confrontation with Creed and his Apostles.
Black Cross: A variation of the Black Claw which is just two slashes in a cross pattern. It is more powerful because of the ovelapping point in the cross but harder because of the trajectory change. He only uses it against Creed in the final fight.
Reflect Shot: Formerly Saya's technique, Train uses this skill as a way to commemorate his friend. When he uses this move on Creed, he was enraged because Train uses "the witch (Saya)"' technique.