Ink of the Soul
"Ink of the Soul" (紫魂ノ墨, purple soul ink) is a term used in Fatal Frame III. It is the ink used to tattoo the Tattooed Priestess in the Piercing of the Soul ritual. It is composed of red and indigo ink, blood of the living and the dead, gathered by the Engravers in the Rite of Purple Ink.
When the priestess is tattooed with this ink, the pain connected to the pain of the living and the dead is transferred to her, appeasing the suffering of the Worshippers.[1]
After the holly has been engraved, the excess ink is washed away in running water from the Other Shore (also known as the Sea of Endless Night).