Dreams, thought, emotion… all are Kokoro's domain. Kokoro may appear in any form at anytime to anyone.
Before Uchu's birth, Kokoro was the Patron of Energy. With the first life, Kokoro abandoned that role, and embraced Consciousness. Hee, previously only Patron of Plasma, was kind enough to take over Kokoro's duties. The world before was simple, but the first life changed all of that.
Kokoro's Hidden form is the subconscious.