God's Greatest Secret

The God's Greatest Secret (のめ, kami no himegoto) refers to a shinki's true name.

Description
When a god names a shinki, they receive the soul's true name and memories at the time of naming. From the shinki's perspective, their memories are sealed away by the seal script imprint of their god-given name. In normal cases, shinki have no interest in questioning their identity or past – Father states that that is simply how they are "made".



Exposure to the Secret
A shinki's lack of interest in their own past fades when they are asked about the topic of their past lives by other beings of the Far Shore. This is often denoted by the cracking of their name's kanji imprint, and it is nearly unheard of for a shinki to survive this event. Shinki who are exposed to the Secret remember their former lives and death, and are consumed by grief & anger, usually turning them into karma ayakashi. When a shinki reaches that point, their soul can no longer be saved.

Although they are capable of ignoring this instinct should they choose to, it appears that gods have a naturally strong aversion against revealing the Secret to shinki. So in most cases, the Secret is very closely guarded by gods. Due to its easily contagious nature and often slow progression, it may be necessary for gods to kill shinki that have been exposed to the Secret in order to prevent its spread.

Surviving the Secret
In rare cases, some shinki are capable of surviving the revelation of the God's Greatest Secret.
 * The Stray: During the conclusion of the Sakura arc, the Stray shows surprise at Sakura's transformation into an ayakashi, saying that "all [Yato] did was tell her her real name." Father also reveals that the Stray has survived the Secret and knows her own final moments - although the specific circumstances surrounding her survival have not yet been revealed, it may have been due to her dying before she was born, having no name and no memories to be revealed.
 * Nana: During the Heaven arc, Nana was affected by Liberation and remembered her final moments and her human name. Though first appearing to be furious, she realized she wanted to die fighting this time too and came back with renewed strength. When Yato remarks that he thought humans were supposed to be obsessed with their lives and death, Nana responds that it's "more painful to see someone you love die."