Soul

The Soul (, Tamashī) is the incorporeal essence of a living being. Its existence and properties are the subject of metaphysical speculation.

Overview
Koala regards the soul as a metaphysical ensemble of a living being's memories and individuality which persists after their death, and the reason some humans devoured by the Chimera Ant Queen retained their memories even after being killed and their bodies destroyed. He theorizes that it may be capable of reincarnation, in particular following a violent death, and possibly even possess a physical dimension as a particle.

13th Hunter Chairman Election arc
Some time after the events of the Chimera Ant arc, Koala finds Kite and tells them about a red-haired girl he killed who resembled him. He shot her in the back of the head as Chimera Ants chased after her, to spare her the torture she would suffer at their hands. Before becoming a Chimera Ant himself he used to be a hitman, and he found himself reliving the cycle of violence after his rebirth. Believing that her soul would be trapped in the same cycle if she died in pain, he shot her hoping to free her. He states that only a few of the hundreds of people eaten by the Queen retained their memories, so most of their souls might have escaped without his help. Since Kite looks nearly identical to that girl, he believes that her sould might have been freed. He adds that no Chimera Ant claimed to have been killed by him, so the souls of all his victims probably broke free from the cycle.



Before his rebirth he did not believe in the soul and viewed consciousness as a mere glitch of a complex brain which would disappear forever after death. However, having retained his memories and the same despised patterns as when he was human, Koala is forced to recognize that he is still himself even after dying. He likens the soul to DNA, as both are extremely small but carrying a tremendous amount of information, and to the infinitesimaly small things that make up the whole universe. Acknowledging that the size of a thing does not affect its power, he reckons that the soul must possess a tremendous amount of it to be able to reincarnate. He wonders if he was brought back to repeat the cycle, even as he wishes to break out of it, because his actions did not match his real desire: he should have shot the grunts chasing the girl, not her, so as to protect himself.

Trivia

 * Koala's views on the soul are reminiscent of the concept of Saṃsāra, with reincarnation being seen as a cycle to escape.
 * If the soul exists as a physical or supernatural essence in-universe, it is possible that, as Koala indirectly suggests, Kite's Crazy Slot number which according to Ging Freecss played a part in saving them transferred their soul into the body of a gestating Chimera Ant (or created that body in the first place).
 * Ikalgo and Leol have retained memories and feelings of their non-human component after being reborn as Chimera Ants, potentially suggesting that, if the soul exists, animals might possess one as well.