Blade of The Immortal - The Kessen-Chu

The Kessen-Chu

A bloodworm (kessen-chu) is an unexplained little worm-like creature, which lives in the bloodstream and tissue in a symbiotic way. It heals all wounds acquired by its host, replacing the missing tissue and organs with their own bodies as well as reattaching limbs. Many of the "scars" on Manji's body are actually worm flesh, holding Manji together like living sutures. However, it is noted that the bloodworms can only heal wounds acquired during infestation and not ones that were acquired prior (such as Manji's eye). They also do nothing to prevent pain. The only way to kill a bearer of the bloodworms is to use a bloodworm poison, although it has been implied that cutting off their head may suffice if it is not reattached quickly. During his battle with Makie, Manji said the only way to stop him would be to cut off his head. But whether this would kill him or just leave him unable to function is debatable, because in his battle with Eiku Shizuma, Manji cuts off his head after poisoning him with his own sword, and he does not die until after the kessen-satsu (blood worm killer) takes effect. Further adding to the debate were statements in Wizard magazine that Manji could survive a severed head, but it would take at least a year for the blood-worms to regenerate that much tissue. While not yet covered in the English version of Blade of the Immortal, another immortal is partially beheaded (to the point where only a flap of skin is keeping its head attached) only for the wound to heal within a few seconds This essentially confirms that Manji's regenerative abilities would allow him to survive a beheading. The time in which it takes for regeneration varies: Manji can reattach a limb within seconds and can partially recover from a bullet or stab wound to the brain. However the wounds to his head did have a negative effect (incapable of moving his lower body or weaker vision). Apparently, the kessen-chu give immortality to its host and everlasting youth (the host retaining the age he/she had at the time he/she was fed the kessen-chu).

It is unknown how to infect a person with the kessen-chu, but Shizuma indicates it takes a lot more than blood to blood contact with someone who's infected.In later chapters the question how to transfer them becomes a major part of the story.