Nephrite (called Nephlite in the English adaptations) is the second of the Shitennou to appear, and the second-highest in rank. Takeuchi describes him as cocky and emotional, saying he will probably get himself killed right off, which he did in the manga. He is the second-oldest, estimated at about 19 years old, and is in charge of the Dark Kingdom's North American division. He is named after the mineral nephrite.

In the manga, Nephrite's primary goal was to locate the Silver Crystal. The loss of the first king Jadeite enraged Nephrite and the desire to avenge his fallen companion was the main driving force behind Nephrite's efforts. Nephrite would use a "shadow" of himself to attack his victims which would possess them and allow his control over their bodies, simultaneously draining their energy in the process. His final and only scheme involved the possession of Motoki who in turn passed this corruption on to Makoto. Mamoru rescued them from the Shadow and in revenge Sailor Jupiter struck down Nephrite and killed him.

In the anime, Nephrite took over Jadeite's position after the latter was banished into Eternal Sleep by Queen Beryl. He criticized Jadeite's methods of collecting energy explaining that he tried to attack too many people at once. Nephrite hypothesized that he could gather more energy from a single person than Jadeite could from a hundred based on a person's intonation with the stars. Nephrite could tap into this natural rhythm to find people who were reaching their maximum "energy potential" and then drain it for Metaria. Nephrite used an alter ego Masato Sanjouin in the anime and assumes the identity of a wealthy businessman and drives a red Ferrari 512TR Testarossa. Although he does act as a typical human, he does occasionally demonstrate some super-human abilities, such as easily leaping over the fence of a tennis court. Over the course of his missions, he inadvertently attracts the attention and affections of Naru. After many attempts to simply gather energy, many of which were deemed successful by Queen Beryl, he resigned his efforts to locating the Ginzuishou. This infuriated Zoisite, the third king, who would relentlessly taunt and ridicule him. Nevertheless Nephrite was able to develop a homing device that would track down the Ginzuishou—in the form of a Black Crystal (Kurozuishou). Oddly enough, the Black Crystal would only react to the presence of Naru and Nephrite correctly assumed it was reacting to the power of her love for the king. In the end Nephrite also developed feelings for the redhead which gave Zoisite the necessary edge to eliminate the former king. Zoisite's minions captured Naru whom Nephrite summarily rescued. In the process he admitted his feelings for the girl and gave a genuine smile, as well as a good laugh. Then, Zoisite's minions attacked again and Nephrite took a piercing vine through his shoulder to protect Naru as well as a direct attack from another of the assassins. In the midst of the attack, Nephrite dropped the Black Crystal, which Zoisite then obtained. The Sailor Senshi arrive to destroy the minions, but Nephrite is already too far from saving, professing his regret for lying to Naru so much and soon died in her arms.