She was introduced in the Sailor Moon S season of the anime and Infinity arc of the manga. Sailor Neptune fought alongside her partner and lover Sailor Uranus in defending the Solar System from outside threats. In both versions of the story, she was elegant, sophisticated, capable of sharp anger, and sometimes cold, whether she was in civilian or Senshi form. She was fully dedicated to her duty as a Senshi. Her powers were based on the sea or ocean (not just water in general like Sailor Mercury).
In the anime, Sailor Uranus often asked Sailor Neptune to distinguish whether a Pure Heart Crystal was a talisman or not, implying that Sailor Neptune had additional powers of perception.
- Neptune Planet Power, Make Up - Used her Lip Rod to transform into Sailor Neptune (used in Sailor Moon S, SuperS, and Stars).
- Deep Submerge - Sailor Neptune sent a blue-green sphere shaped like Neptune toward her target.
- Submarine Reflection - Sailor Neptune used one of the talismans, the Deep Aqua Mirror, to either reveal an enemy's weakness or attack with a powerful wave of water.
- Sailor Neptune's (S) dominant color was sea-green (tiara gem, choker, collar, gloves, skirt, and heels) and her accent color was navy blue (bows). Her earrings were white studs, her collar had no stripes, and her choker had a sea-green gem with gold accents attached to it. Her shoulder pads were the same as the others. Her gloves were wrist-length (rather than elbow length). Her heels had criss-crossing straps up the ankles, like ballet slippers.
- After the "Super" upgrade (Stars), her earrings remained the same, her choker had a star attached to it, her collar had one white stripe, the center of her front bow was a heart, she had one translucent shoulder pad, and the back waist bow was enlarged and lengthened. The length of her gloves remained the same.
- Neptune Planet Power, Make Up - Used this phrase to transform into Sailor Neptune.
- Neptune Crystal Power, Make Up - Used the Neptune Crystal to transform into Sailor Neptune.
- Deep Submerge - Sailor Neptune sent an energy blast at the enemy.
- Submarine Reflection - Sailor Neptune used the Deep Aqua Mirror to either reveal an enemy's weakness or send an energy blast.
- Submarine Violon Tide - Sailor Neptune used her violin to send an energy blast at the enemy.
- Galactica Violon Tide - This attack was used by Sailor Neptune when she was under Sailor Galaxia's control in the Stars arc.
- Sailor Neptune's first costume in the manga was completely identical to the anime version.
- Her brooch changed from a circle to a heart after Sailor Moon first transformed into Super Sailor Moon.
- After the "Super" upgrade, her costume was almost identical to the anime version, but the length of her gloves extended to her elbows, and the star on her choker had a sea-green gemstone in the center.
- After the last upgrade in the Stars arc, her choker was V-shaped and the center of her front bow was a green five-pointed star. She had round light green puffed sleeves with two strips of darker fabric attached to the bottom. Her gloves became longer, reaching to her upper arms. Her belt consisted of two ribbons, one sea green and one light green, with two long, thin back ribbons, clipped together by a golden five-pointed star. Her back bow was light green. Her skirt became two-layered, the top layer being sea-green and the bottom a lighter green. Her boots were knee-high and white, and each had a sea-green V-shaped border with a golden five-pointed star at the top. Her tiara gem was a sea-green five-pointed star and her earrings were sea-green, dangling five-pointed stars.