Darien/Mamoru Shields is one of the major characters in the Sailor Moon series. His transformed state is Tuxedo Mask. He is also Prince Darien, who is in love with Princess Serena. In the future, he will marry Serena and become King Endymion, as he is referred to by Pegasus in Sailor Moon Super S.
For the first half of Sailor Moon, Darien is always annoying Serena and calling her "Meatball head" (Dumpling Head in Japanese version). As Tuxedo Mask, he often shows up to help Sailor Moon fight the Negamonsters. He made his presence known each time by throwing a red rose. Sailor Moon fell in love with him. In Episode 10, he fought Jedite but was supposedly killed. After Jedite's defeat, and subsequent death, Tuxedo Mask returned, having survived the battle.
When Neflite attempted to use Tuxedo Mask as Sailor Moon's weakness in Episode 16, he discovered that Darien was Tuxedo Mask (this is the first episode that reveals this, but before Neflite finds out).
While Zoycite was collecting rainbow crystals, Tuxedo Mask got two of them. He even left Sailor Moon a Star Locket as a symbol of their love and affection. In Episode 29, Zoycite tricked him, disguised as Sailor Moon, and stabbed him. She nearly got the crystals from him, but was attacked by Sailor Venus at the last second.
Zoycite, under orders to turn him evil, challenged him to a battle over the rainbow crystals, however she double-crossed him, as Malachite took them. Darien scratched Zoycite's face, so she tried to kill him in revenge, forcing Serena to transform into Sailor Moon in front of him. He then transformed into Tuxedo Mask. Zoycite seriously injured him with an ice crystal. As punishment, Queen Beryl killed Zoycite. She and the Negaforce then turned him evil.
As Prince Darien, he often got into arguments with Malachite, and even helped the Sailor Scouts out a few times (as he did not want Sailor Moon killed, saying their mission was just to get the silver crystal from her). As evil Tuxedo Mask, his presence was made known by throwing a rose that was now colored black.
In Episode 37, Tuxedo Unmasked, he was sent to recapture the rainbow crystal carriers; although the Seven Shadows were killed when Sailor Moon healed the carriers (which was the basis of Malachite asking why they were doing this), their power still remained, and Beryl wanted to use their power to create an invincible shadow warrior, but he was healed by Sailor Moon, and then recaptured by Beryl, who began to erase his memories and brainwash him again.
In the final episode, Queen Beryl sent Darien to fight Sailor Moon. She tried to heal him, but nothing worked until she got him to touch the Star Locket he gave her in Jupiter Comes Thundering In. Darien then injured Beryl by throwing a rose at her just as she was throwing a spiky crystal at them. However he himself seemed injured, possibly even killed, by the shards of crystal.
After the final defeat of Beryl and the Negaforce, Darien returned to a life on Earth with no memory of being Tuxedo Mask. His spiritual form would take that of the Moonlight Knight.
Sailor Moon R
For the first thirteen episodes, against Alan and Ann, the role of Tuxedo Mask was replaced by the Moonlight Knight, whom Sailor Moon initially believed to be Darien, but this seemed to be proven false when Moonlight Knight and Darien appeared at the same time against Cardian Nacrid. He used a white rose to make his presence. In Episode 13, Darien regained his memories during the fight with Alan and Ann. The Moonlight Knight revealed himself to be the physical form of Darien's desire to protect Serena. He then merged with Darien again.
After the appearance of Rini, Darien began having nightmares telling him to avoid Serena or else the world would be destroyed. From here, Darien broke up with Serena, though he still helped fight the Negamoon Sisters' droids. Eventually, Darien and Serena stopped avoiding each other. When they traveled into the future, they met Darien's future self, King Endymion, who told them that he gave Darien the nightmares simply to test his affection for Serena and see how powerful it was, because Prince Diamond will try to turn them against each other. He is also revealed to be the husband of Neo Queen Serenity (Princess Serena's future self) and father of Rini.
Tuxedo Mask often helped the Sailor Scouts out against the Bureau of Bad Behavior in Sailor Moon S, and against the Dark Moon Circus in Sailor Moon Super S. When Fish Eye targeted him to search his dream mirror for Pegasus, she fell in love with him, and was the first of the Amazon Trio to question what they were doing.
He was unable to participate in the final battle against Zirconia, the Amazon Quartet, and Queen Nehelenia because Nehelenia plunged the world into darkness and began to suffocate it with spiderwebs, causing him agonizing pain, as his life force was synchronized with Earth.
- Rino Romano (1st half of Original Series)
- Toby Proctor (2nd half of Original Series and 1st half of R Series)
- Vince Corazza (2nd half of R Series onwards)
- Darien has only specifically been targeted once by the villain while searching for something inside him, and that was when Fish Eye looked into his dream mirror in Sailor Moon Super S. He is not one of the rainbow crystal carriers that Zoycite searches for, and he has never had his Pure Heart stolen.
- Darien is the first character to be kidnapped and brainwashed into becoming evil by the bad guys.