Cain is a young boy who stars as the protagonist of Needless 0.
At first, Cain regarded Needless with suspicion and fear, like the rest of society led him to believe. When he realized that he himself was a Needless, he expressed doubts over using Voice Power. However, Adam's advice encouraged him to ultimately embrace his newfound ability.
In 2132 AD, two years after the conclusion of the Needless storyline, Cain attends school near the Black Spot that was formerly Tokyo. His father had been "exterminated" on the grounds that he was a Needless, so Cain had received some financial aid as compensation. When one of his classmates tries to bully him into giving them money, Cain immobilizes him by shouting: "Don't touch me!"
As Cain reunites with his friend See, he realizes, much to his horror, that he is actually a Needless. See's words about Needless extermination does little to comfort him. Rather than tell See about his ability, Cain decides to travel into the Black Spot alone and learn more about the Needless. Although the (oddly familiar) gate guard tries to convince him otherwise, Cain bribes him by pawning a watch.
Cain soon runs into trouble when he encounters two large Needless resembling Buddhist monks: Shikisoku and Zekuu. Before they can "force him into Nirvana," See arrives and they escape together. See confesses that she entered the Black Spot to write about the Needless for her summer research project.
Eventually, the pair arrive at a church where they meet the nun Adam Neuschwanstein, who bears an uncanny resemblance to Eve Neuschwanstein. However, when Cain asks Adam if she is a Needless, she denies it. Adam plans to introduce them to Mother Black, the Needless who runs the church, but their conversation is interrupted by the arrival of Shikisoku and Zekuu. Mother Black arrives to defend them, and allows Adam to give their assailants a "God's Judgment." Cain confronts Mother Black, yelling that Adam could never survive against a pair of Needless. Much to his surprise, Adam uses the Zero Fragment to defeat Shikisoku easily.
When Zekuu takes Cain as a hostage, Cain uses his Needless power to immobilize him long enough for Adam to deal a decisive strike. With the monks placated, Cain asks to speak with Adam alone. Cain admits to her that he might be a Needless and that he doesn't know what to do about it. Adam tells him that his power will get weaker if he chooses not to use it, so the decision to keep the ability or not was up to him. This exchange is interrupted when See crushes Zekuu's arm, revealing herself as Adam Neuschwanstein's experimental successor, Adam Cyclops. Adam Cyclops declares that her mission was to recover her "older sister," the failed experiment, much to Cain's disbelief.
See crushes Mother Black and Adam Neuschwanstein with her ability, Needless Mutilation. Cain rushes to Adam's side in a state of shock. Adam reassures Cain that although she is a Needless, as long as she is "needed," then she will never be defeated. Adam uses the Zero Fragment to memorize Cain's Voice Ability, which she uses to immobilize See and annihilate her with her own technique, Needless Mutilation. In the end, Cain decides to stay with Adam and Mother Black at the church, having embraced his status as a Needless.
Powers and Abilities
Fragment: Voice Power/ Kotodama - Allows cain to command individuals, even against their own wills.