Kurau&#039;s Rynax Pair. She emerges from Kurau&#039;s body ten years after the incident which fused her with Rynax. Christmas has the body of Kurau in her younger years albeit with a decidedly less tomboyish appearance. Although seemingly innocent and naive, Christmas seems to have an intuitive understanding of others as well as an ability to learn very quickly. (For example, she reads a cookbook and produces a full dinner, on her first day out in the world.) Eventually she vows to protect Kurau, just as Kurau has protected her.  ~wikipedia

In a world of mercenary agents, Kurau is a martial arts master and elite thief—but she has a secret. Her body has been fused with a binary alien life form called the Rynax. Every moment Kurau lives is lived twice, one alien sharing her consciousness, the other still waiting to be born. The truth about Kurau has begun to spread, and now the ultimate agent is the ultimate target.
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(Source: Crunchyroll)

Single volume adaptation of the original BONES anime of the same name.

A two volume novel adaptation of the BONES anime series.