Neo-Queen Serenity was the Queen of Crystal Tokyo and the resurrected Silver Millennium. She was an extremely important character in the series, and she first appeared in the Black Moon story arc.
Neo-Queen Serenity was the future form of Sailor Moon. She ascended the throne along with her husband, Endymion, and ruled all of Earth from the Crystal Palace (situated in what was formerly the Juuban district) with the power of the Silver Crystal. The details of her ascension to the throne and the subsequent attacks varied according to the source. In both the anime and manga canon, Neo-Queen Serenity sent her child, Chibiusa, into the past to train to be a Sailor Senshi after the threat in the future ended.
Neo-Queen Serenity was much more composed and regal than her younger self, but there were hints that she still retained some of her goofy traits. For example, she sent an unusually cute letter with Chibiusa to Usagi and Mamoru, which demonstrated the fact that even after several centuries she was still unable to write well in kanji. She also had a penchant for using smiley faces in her letters, as well as heading them with a cute drawing of herself. Also, Diana spoke of the future King and Queen both falling ill just before stuffy official ceremonies, and miraculously recovering as soon as they were over.
Some time after the twentieth century the Earth was struck by an unspecified disaster, and after it was saved by Usagi in the 30th Century she ascended to power as Neo-Queen Serenity. Through the power of the Silver Crystal the people of the Earth became functionally immortal. Once she became Queen, Serenity ceased to age, and continued to retain her youthful appearance for well over ten centuries.
The Black MoonEdit
Some time after Neo-Queen Serenity came into power, she initiated a cleansing of all of the people on Earth using the Silver Crystal. Some people refused to be purified and they rebelled. The King and Queen defeated the rebellion and those who still refused to be cleansed fled from Earth to the desolate planet of Nemesis.
Some centuries later, the descendants of the first settlers were confronted by a new influence. Calling himself Wiseman, this newcomer set himself up as the Black Moon Clan's advisor and advised Prince Dimande to attack Crystal Tokyo directly. Filling everyone's already disgruntled mind with hatred towards Earth, and using the Evil Black Crystal to amplify their considerable powers, Wiseman steered the Black Moon towards the fateful attack on Earth which incapacitated both the king and queen and almost destroyed Crystal Tokyo.
The queen was encased within a special crystal after she was hit head on by a blast of black energy, her condition so grave that Sailor Moon's own crystal couldn't wake her up. However, she was still semi-conscious despite her apparently comatose state, and was able to exert some of her powers. She projected her spirit into Sailor Moon in order to break Wiseman's hold over Black Lady, and later spoke to Sailor Moon and Chibiusa in the spirit plane while returning them to their bodies.
In the manga Usagi became queen regent at age 22, the same year she gave birth to Chibiusa, after leading the world away from a second ice age. Through her power and the power of the Silver Crystal the people of the Earth became functionally immortal. Once she became Queen, Serenity ceased to age, and continued to retain her youthful appearance for well over ten centuries. The Inner Senshi never aged physically past the age of 22, Haruka and Michiru stopped aging at about 24, Hotaru at an undetermined age, and Setsuna was already essentially ageless.
Neo-Queen Serenity stated that she had lost most of her powers as a Sailor Senshi as the price of becoming Queen, though what exactly that meant was never specified. This was why it was so imperative that her child awaken as a Senshi. Even without the ability to transform, Serenity still demonstrated great powers in the manga, such as the ability to upgrade the powers of the the twentieth-century Sailor Senshi.
The Black MoonEdit
In the beginning, Crystal Tokyo was an extremely peaceful place until Death Phantom appeared, corrupting the citizens' minds and inciting violence towards the queen. In response, Neo-Queen Serenity used her power to capture and banish Death Phantom to Nemesis, as she did not believe in executing humans. But Death Phantom was no mere human: he was an aspect of Chaos, and Nemesis was actually a piece of himself, able to bend time and space.
After several centuries of relative peace, Death Phantom reappeared, this time recruiting a group of rebels disillusioned by the queen to attack Earth. They did this by planting a Black Crystal monolith on the planet, killing nearly everyone on Earth in the process.
During the attack, unfortunately, the queen also became a victim of the Black Moon when she went out of the Crystal Palace to look for Chibiusa, and was hit by Prince Dimande's attack. She was quickly transported into the palace, where she lay comatose. Despite her incapacitated state, the queen could still think, sense evil, and even use her power in a limited way, such as when she repelled Black Lady from the Crystal Palace.
Neo-Queen Serenity awoke after Chibiusa transformed into a sailor soldier, and she aided Sailor Chibi Moon in her attempt to reach Sailor Moon and defeat Death Phantom. She also bestowed new power-ups on the soldiers, including the Spiral Heart Moon Rod and the Cosmic Heart Compact. She was also the one who gave new titles to the Inner Senshi: Sailor Mercury was the soldier of wisdom, Sailor Mars was the soldier of war, Sailor Jupiter was the soldier of protection and Sailor Venus was the soldier of love.
In the musicals, Neo-Queen Serenity was played by Fumina Hara and Marina Kuroki.
Though Neo-Queen Serenity was unable to transform into Sailor Moon, she was in many ways much stronger than her younger self. She had a much greater control over the Silver Crystal and was able to use it over a very great distance, and even control it from another time.
Using her power, she could project herself through time and space, which was a power comparable only to Sailor Pluto's. She could revive people in mass numbers and do so with seemingly little damage to herself, despite the consequence of death for using the Silver Crystal's power. In the manga, she also had the ability to create magic objects like weapons and stronger transformation items for the Sailor Senshi. It is also likely that she was the sole architect of the Crystal Palace, as the structure was indestructible and had a great power comparable to hers.