The Shitennou (四天王, Shitennō?, Four Heavenly Kings) are the commanders of the Dark Kingdom working directly under Queen Beryl. The Shitennou provide the major antagonistic force for the beginning of every version of the series—manga, anime, musicals, and live-action. The group's title, shitennou, comes from Buddhist mythology. Each member has epaulettes on his uniform, which indicate their respective ranks.
In the manga, the Shitennou originally functioned as the four guardians of Earth's crown prince Endymion. They were led astray during the time of the Silver Millennium, finally selling their souls to the Dark Kingdom and becoming Queen Beryl's servants. When reincarnated in the 20th century, they again fall prey to her and obey her every command, but retain a sense that they need to seek out their real master and aid him. In the manga, they continue to appear after the first season as spirit-advisors to Mamoru, the reincarnation of Endymion. This backstory was not included in the anime, but was reintroduced and built upon for the stage musicals and even more so live-action series. It is also hinted that they were in romantic relationships with the remaining Sailor Senshi. Kunzite and Venus, Zoicite and Mercury, Jadeite and Mars, and Nephrite and Jupiter were the hinted pairings in the manga.
In DiC's English adaptation of the anime, the Shitennou were human-like beings from the Negaverse, an alternate dimension of evil, and had only a vague understanding of human ways. From dialogue between Nephlite (Nephrite) and Zoycite (Zoisite), they were even required to take classes in human psychology to blend in. Zoisite was also changed from a male to a female named Zoycite.
The first musical, Sailor Moon - Gaiden Dark Kingdom Fukkatsu Hen and its revision featured all four Shitennou. During a ball, Princess Serenity and Prince Endymion sang Waltz ni Koi wo Nosete, and the Shitennou were paired with their respective partners, however, this romance was short-lived as Sailor Mars, Sailor Jupiter, Sailor Mercury, and Sailor Venus were each forced to fight Jadeite, Nephrite, Zoisite and Kunzite respectively. While the Guardian Senshi won in each case, the Shitennou used lies and trickery to harm each of the soldiers, resulting in members of both sides dying.
In the 1997 musical Eien Densetsu, only Kunzite and Zoisite appear. Zoisite flirts with Ami, and even sings a duet with her (Itsuwari no Forevermore, lit. Lies Forevermore). Ami only responded to Zoisite's flirting because he subtly brainwashed her. They would have shared a kiss if they weren't interrupted.
In the Sailor Moon: Another Story video game, the Shitennou appear as ghosts who help four of the Sailor Senshi get the respectul gems of each of the Shitennou when Momoru ends up injured by the Opposito Senshi.
In Starlights - Ryuusei Densetsu, the implied romance between the Shitennou and Guardian Senshi can be seen in various situations. The Shitennou are sent to flirt with the Senshi to make them distracted. The Shitennou in their human identities protect the Senshi who are also in their civilian identities, from Sailor Galaxia. They can also each be seen flirting in their respective couples, as the Shitennou present gifts to the Senshi in a park. They take the alies of J. Taitou, Light Mifune, Saitou Izou and Saitou Kun and are known as a group called the Jewel Meterias. They claim to deal in gemstones and bring their business to Japan by being a part of Michiru, the Animamates' and Three Light's joint concert.
The musical Kakyuu-Ouhi Kourin had a group that which called themselves the Neo Shitennou. The members of the Neo Shitennou were Kunzite, Hematite, Hiddenite, and Kalunite. There was no explanation for changing their names, but Hematite, Hiddenite, and Kalunite looked identical to Zoisite, Nephrite and Jadeite respectively. The group worked with the reborn Queen Beryl under Sailor Galaxia, though the five of them were plotting to get out of Galaxia's rule.
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