There are 8 different Eidolons (Effects) in Collective Unconscious that Minnatsuki can collect (including the Instructions).
This page lists all of the different eidolons in Collective Unconscious, along with their locations and instructions on how to get them.
Effects
Rodentia
(齧歯類)
*squeak squeak*
(Eidolons recommended to have before retrieving: none)
Appearance: Minnatsuki becomes partially a rat, with rat ears and a rat tail.
Passive Effect: None
Action: Minnatsuki transforms into a small rat.