Caerula Animus
The Caerula Animus (Latin for "Azure Lifeforce") is a Collectible in Mizuki & Caerula Arbor.
The surviving core organ of the "Firstborn" that devoured Its birthplace and soon died afterwards. Only the Seaborn are able to assimilate it, but only humans are able to understand the grief contained within. Alas, even for those whose evolution never ends, their – Their – suffering will always persist.
Effect
Causes the player to lose 50 Light and a random Operator to be afflicted with Rejection when obtained.
| “ | Undercurrents surge beneath the tide; the blood of the "Firstborn" leads Skadi back to We Many, and the Silence draws near. | ” |
| —Message after the Caerula Animus is obtained |
If the player has the Caerula Animus, clearing 5F will cause the player to enter 6F instead of completing the run with Destiny of We Many as the Dreadful Foe, which will complete the run with the Price of Peace ending when cleared.
The player must have the Caerula Animus for Encounter: Paean where the 
"Last Refrain" is obtained to appear.
Acquisition
The Caerula Animus may be obtained from the namesake Encounter, which will only appear from 4F when the player has the 
Bishop's Research.
Since Encounter: The Beginning where the Bishop's Research is obtained will only appear in the following runs after the player had completed a run with the Age of the Silence ending, it is impossible to obtain the Caerula Animus before then.