Nyxathta, while a kijikaiaku from Gaia, does not originate from the very dimension he has come to find home. Native to a dimension where the timeline of events went very differently, one where the kijikaiaku lost the war of The Thinning and humanity effectively destroyed the planet with pollution and war. Rescued by a keirolté, Nyxathta's own energy was irreversibly corrupted by his native dimension, making him reliant on his very saviour for survival, for not even Gaia can purify him.
Though Nyxathta has since learned how to contain the corruption within himself, the first kijikaiaku he summoned, Vyxréth, was summoned before he figured it out, resulting in the younger kijikaiaku's own energy being tainted permanently.
Nyxathta's memories are damaged and foggy, and he often has difficulty remembering who he is, with his keirolté companion often being the main being keeping him from losing all sense of self.