The Yakushiji Symbiote is a mysterious creature that inhabits Tenzen Yakushiji's body and the source of his immortality.
Appearance[]
In its dormant state, the symbiote has the appearance of two wart-like growths that stay on each of Tenzen Yakushiji's ears, which form together when healing his body. In this state, the only visible characteristics of it are dark (sometimes red), menacing eyes similar to Tenzen's, and a mouth. Sometimes, while in the process of tending to its host's wounds, something similar to hands are slightly visible. And, on only one shown occasion, the image of a small, yet disfigured body can be seen.
Biography[]
In the manga, the Yakushiji symbiote, according to Ogen, is Tenzen Yakushiji's twin brother with whom he merged with inside their mother's womb shortly before being born.
However, in the anime, Ogen stops just before telling Oboro where she believed the parasite came from, leaving its identity ambiguous.
Personality[]
The symbiote is at least partially intelligent as it will not initiate the self-healing process while suspicious characters are nearby to ensure that they will not hinder Tenzen Yakushiji's recovery in any way (as seen with the delayed recuperation during the time when Tenzen's body was carried around by Saemon Kisaragi while searching for some suitable clay to copy his appearance).
Abilities[]
Regeneration: The symbiote has the ability to heal any wound that may be inflicted on Tenzen Yakushiji's body by simply "eating" them. This ability is so proficient that it is even able to mend his head back onto his neck if severed; however, his head must be held where it was chopped off in order to heal correctly. According to Tenzen, the only way to kill him is by cutting off his head or burning his body to ash, meaning the symbiote is obviously unable to cure injuries this drastic.