The Neptune Crystal is Michiru Kaio's Sailor Crystal, the gem that fuels her rise into her stronger guardian forms. It surfaces in the manga and in the film Sailor Moon Eternal, having come to her as a gift from Hotaru Tomoe.
As the Sailor Crystal tied to Michiru Kaio, this jewel represents the core of her power as Sailor Neptune. It belongs to the set of crystals the outer guardians receive, and it appears within the manga continuity as well as the Eternal movie.
Michiru draws on the crystal to reach both Super Sailor Neptune and Eternal Sailor Neptune, invoking the phrase Neptune Crystal Power, Make Up to complete either upgrade. The gem is what carries her beyond her base guardian form into these heightened states.

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The Neptune Crystal is Michiru Kaio's Sailor Crystal, the gem that fuels her rise into her stronger guardian forms.
Michiru invokes the phrase Neptune Crystal Power, Make Up while holding the crystal to complete her upgrade into Super Sailor Neptune or Eternal Sailor Neptune.
Michiru comes into possession of the Neptune Crystal through Hotaru Tomoe, who hands the gem to her.
The Neptune Crystal appears within the manga continuity as well as in the film Sailor Moon Eternal.
No one; Michiru Kaio is the crystal's owner and only wielder.
Looking for more on Neptune Crystal? The Sailor Moon Wiki on Fandom has a dedicated page with community notes.
View on FandomThis content is original writing by Daddy Jim Headquarters based on the Sailor Moon anime series, manga, and official materials. Sailor Moon was created by Naoko Takeuchi, published by Kodansha, and animated by Toei Animation. All rights to Sailor Moon and its characters belong to their respective owners. Episode and chapter references are cited where applicable.
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