Guardian Neptune

She is a diminutive, fairy-like spirit who keeps aloft in the air, surrounded by a green shimmer. Every feature otherwise matches Super Sailor Neptune. In the manga's black-and-white pages that shimmer reads only as a wide circle around her with no visible color, while Crystal draws the green light cleanly along her outline.

She is best understood as an aspect of the Sailor Guardian she belongs to, part of Michiru in the same manner as her Sailor Crystal. Her purpose is to advise and to relay, standing at her princess's side when the moment calls for guidance or for shared defense of the solar system.

During the Dream chapters she emerges in Elysion as Super Sailor Moon first summons the Holy Moon Chalice, when the solar system soldiers shift into their princess forms and each is met by her power guardian. Hovering before Princess Neptune, the spirit tells her to channel power from Triton Castle into the chalice, lifting Usagi to Eternal Sailor Moon and letting Michiru's Neptune Crystal Power, Make Up bring out Eternal Sailor Neptune for the first time; she then disappears once the castle is called upon. In the Stars arc, as Shadow Galactica's assault on Earth intensifies, Michiru joins Haruka and Setsuna in retreating to their castles to raise a protective shield and gather intelligence. Guardian Neptune is understood to be present with her at Triton Castle, though not pictured. When Sailor Galaxia reaches Charon Castle and cuts short their transmission, the spirit is destroyed alongside her princess.