The Celestial Spirit King, who governs the entire spirit realm and enforces rules among all spirits, stands as the most formidable of them all. It remains a mystery whether he grants his key to humans or if he even possesses one.
Aquarius reveals that only a Celestial Wizard capable of summoning three zodiac keys simultaneously can call upon the Celestial Spirit King once. Another condition for his summoning is "Summoning with a Price." By paying the heavy price of destroying Aquarius' key, Lucy manages to summon the Celestial Spirit King. Consequently, Lucy will never be able to see Aquarius again.
