TV-Series
Description
Cain is a character exclusive to the anime adaptation of Bleach, appearing only within a flashback sequence. He was a young male member of the Bount race, a group of artificially created beings with eternal life who must consume human souls to survive. Cain was discovered by the Bount leader Jin Kariya, who brought him to live under the care of another Bount, Gō Koga, in the rural European countryside during the late 19th or early 20th century. Before coming to live with Koga, Cain had a very difficult life, the details of which he preferred not to discuss, implying a past filled with hardship and persecution.

In terms of appearance, Cain bore a striking resemblance to the series' main protagonist. He had cropped, reddish-brown or light brown hair and icy blue eyes, and was often seen with similar gestures and expressions to Ichigo Kurosaki. His clothing was typical of the time period, consisting of a blue cloth jacket, a white button-up shirt with rolled sleeves, dark trousers with suspenders, and a purple or newsboy-style cap. This physical similarity extended to facets of his personality. Like Ichigo, Cain was impulsive, brave, and hot-headed, but also exhibited a quiet and somewhat melancholic demeanor. He did not like to run from a fight, a trait seen when he was attacked by villagers who discovered his identity as a Bount. However, his nature was also more impatient and reckless, a flaw that would ultimately lead to his demise.

Cain's primary motivation was a desire for self-sufficiency and strength. After witnessing the power of Koga's Doll, a creature named Dalk, Cain became determined to summon his own. Koga, who had taken a paternal liking to the boy and treated him like a son, gave Cain a book of rites written by Kariya that contained the instructions for summoning a Doll. Despite Koga's explicit warnings that he was not yet ready or properly prepared, Cain's impatience drove him to attempt the summoning on his own.

The relationship between Cain and Gō Koga is the most significant in his story. While there was initial tension between the two, Koga grew to care deeply for Cain, and Cain in turn came to admire Koga greatly, desiring to become as powerful as his mentor. Cain lived on Koga's farm, helping with daily chores with great efficiency, and for the first time, he experienced a place where he was not pursued or treated as a monster. Cain's death had a profound impact on Koga, who carried a great deal of guilt over the incident, believing he should have prevented it. This tragedy led Koga to vow never to allow another young person to die in battle on his watch.

Cain's development is cut tragically short by his own fatal error in judgment. One night, despite not being prepared, he summoned his Doll, Waineton. Initially, Waineton appeared as a small, bright green, bean-like creature. It told Cain it was tired and needed to rest, but Cain insisted it show its powers like Dalk had. Giving in, Waineton agreed to demonstrate its true form only if Cain could pass a test of his worth. It then revealed its authentic appearance, a gigantic, uncontrollable praying mantis-like creature, which immediately killed its own master before he could prove his strength. Cain died reaching out to Koga, expressing his fear and his desire not to die.

As a Bount, Cain possessed the inherent racial abilities to detect spiritual beings and energy, as well as the need to feed on human souls. He was also a capable hand-to-hand combatant, having undergone a period of training with Koga that gave him respectable fighting skills and enhanced strength, enough to punch through a wooden training dummy. However, he never lived long enough to fully develop or control his primary power, his Doll Waineton, which ultimately destroyed him.