He gets brainwashed by Queen Metallia. As Dark Prince Endymion he fights against Sailormoon but never really hurts her and there are moments when his black roses of death change back into Tuxedo Kamen's red roses of love. However after a second brainwashing he tries to kill Sailormoon. But she believes in their love and offers him the star locket. He touches it and is healed. Queen Beryl attacks
Sailormoon, Mamoru protects her and dies. Before Sailormoon goes to fight her final battle (she knows that she will not survive it) she says good-bye to her one true love.

After their second rebirth both have lost their memories again. Ginga Seijuurou (Ail (Earl) disguised as a human boy) has a crush on Usagi. He buys her roses and plays his magic flute to win her love. Of course he has no chance. Usagi gets her memories back first. She is shocked when she finds out, that Mamoru doesn't remember their love any more. Mamoru seems to like Natsumi (Ann disguised as human girl) more than Usagi. But Usagi does not give in , she fights for his love but without any success. Instead of
Tuxedo Kamen the Tsukikage no knight (Moonlight Knight) saves Sailormoon whenever she is in danger. Sailormoon is torn between Mamoru and the Tsukikage no knight. Finally it comes to light that the Tsukikage no knight is but a separated part of Mamoru' s personality. When they become one again Mamoru' s memories are restored and nothing seems to be able to endanger their love any more....
Usagi even introduces Mamoru to her parents and calls him her boy friend (her father is not very pleased to hear it). But since Chibi Usa has appeared, Mamoru has terrible nightmares. During these dreams a voice predicts the death of the Moon Princess if Mamoru doesn't separate with Usagi. Therefore Mamoru says to her that he wants to end it with her and that he doesn't love her any more. Usagi is shocked. She reminds him that they have been in love in their former lives but he says that it is over with her. Usagi's
heart breaks. She cannot understand him because Tuxedo Kamen still comes to Sailormoon' s aid. He even saves her from a deadly nightmare spell by kissing her. She does everything to get him back. She tries magic amulets, love potions, cosmetics, jewels, handmade lucky bracelets ... but she always fails. But then she has the same nightmare... She runs to his flat and tells him that she wants to be with him even if this means that she has to die. Mamoru says that he won't let it happen and sends her away. Later they realise that they must stick together to save the future. Mamoru can not withstand the love glowing in her eyes any more and he gathers her into his arms again. During their journey to the future they find out that their nightmares have been sent by King Endymion from Crystal Tokyo in order to put their love to a test.
In Crystal Tokyo Mamoru and Usagi see their future. Together they will reign over Crystal Tokyo and Chibi Usa is their future daughter. But this future can only happen if they succeed in protecting present Tokyo...
Prince Demando wants Queen Serenity to be his love and he realizes that Sailormoon is her former self. That's why he captures Sailormoon and carries her to his palace. He wants her to stay there forever and he tells her that she will be his queen. Of course Sailormoon refuses to become his bride, so Demando uses the hypnotic powers of his third eye to force her to obey. He tries to kiss her but Sailormoon senses that Tuxedo Kamen is coming to save her and thanks to Esmeraude' s jealousy they escape. When Demando and Black Lady create the giant Black Crystal in the middle of Tokyo, Sailormoon gets caught a second time. Again Demando tries to force her to love him. This time Sailormoon withstands his dark powers by remembering her true love.
But Demando is not the last danger their love has to face during Sailormoon R. The alien Fiore, a childhood friend of Mamoru is jealous of Usagi. He tries to kill Usagi/Sailormoon but Tuxedo Kamen protects her and is injured. Fiore takes him to his comet and Sailormoon is very sad. She thinks that it is only her fault. During her fight with Fiore on his comet, she nearly gets killed by his dark powers. Tuxedo Kamen escapes the healing crystal and although he is still weak he uses all his strength to throw the red rose, the symbol of his love. Its magic destroys Fiore's armour and saves Sailormoon. After they have
defeated Fiore and the Kisenian Flower, Sailormoon changes into Princess Serenity in order to save them all. She has to use the Ginzuishou and dies in Tuxedo Kamen's/Prince Endymion' s arms. This time his kiss, (and the nectar of Fiore' s flower) brings her back to life.
Another battle is won but new villains appear and Usagi's brooch loses its powers. The Daimons, monsters created by the Death Busters, are very strong and the other senshi are no match for them. The
Daimon Nekonneru reflects all their attacks. Usagi tries to transform but the brooch doesn't work. She can't help her friends and she can't help Tuxedo Kamen who has come to their aid. Tuxedo Kamen tries to cover the helpless Usagi and gets severely hurt. He tells her to flee but she says that she will stay with him. She takes his hands and a light appears. They have a vision. They are Endymion and Serenity again and the power of their love creates the Spiral Heart Moon Rod and Usagi gets a new brooch with a heart shaped Ginzuishou. Usagi transforms into Sailormoon and destroys the Daimon, another victory based on the power of their love.
One day Usagi is very disappointed because Mamoru doesn't know that it is her birthday and refuses to buy her a present. As soon as Rei tells him about Usagi's birthday he buys her beautiful glass shoes. He doesn't know that there is a Daimon's egg/seed in one of them. As soon as Usagi tries the shoe on, the Daimon appears and steals her heart crystal. She also looses her brooch. Tuxedo Kamen saves her, his roses create an energy field around the Daimon. Without her brooch Usagi can't transform into Sailormoon and they have to flee. The Daimon chases them and they get caught by him and Kaolinite.
Tuxedo Kamen fights against the Daimon and tells Usagi to run away. She tries to flee again but Kaolinite stops her and Tuxedo Kamen gets trapped inside an glass block. Usagi is willing to give her heart crystal (and her life) to save him. Thanks to Uranus, Neptune and the Inner Senshi she gets her crystal back and after the Daimon is defeated, Tuxedo Kamen is free again. Sailormoon is very happy. Finally they defeat the Death Busters, but then the Dead Moon Circus is threatening the peace on earth.
Usagi doesn't know that a student from Mamoru's university, a pretty girl named Saori, has a crush on Mamoru. Chibi Usa fears that Usagi might lose Mamoru's love because Saori is more beautiful and more intelligent. Other students think that Mamoru and Saori are the ideal couple. Usagi tells Chibi Usa that she never doubts Mamoru's love. After Saori and Mamoru have gone shopping together Saori wants to tell him about her feelings. But Tigers Eye appears and goes after Saori's dream mirror. He uses his knives to pin Mamoru to the stairs. Mamoru is helpless but then Super Sailormoon and Super Sailorchibimoon come to their aid. The Lemure Pooko-chan, a big balloon, wants to press her face on Mamoru's so that he will not be able to breath and die. But Super Sailormoon is willing to sacrifice herself for him and gets between Mamoru and the Lemure. She begins to struggle and Mamoru desperately calls out her name. He rips his arms free from the knives and stabs Pooko-chan. Super Sailormoon is okay, together with Super Sailorchibimoon she destroys the Lemure. Saori watches her and Mamoru looking at each others eyes. She knows that she can't beat the girl who protects the dreams of this world.
Fish Eye wants to win Mamoru's love and tries everything to get a kiss from him. But Mamoru doesn't want to kiss him because he loves Usagi for her beautiful dreams. Fish Eye is hurt and knocks out Mamoru's dream mirror. After he has searched the mirror for Pegasus (Super Sailormoon is not able to help Mamoru), he cannot bring himself to destroy the mirror but kisses the unconscious Mamoru instead. Sailormoon is very happy that he has his dream mirror back.
Some time later Mamoru begins to suffer from a mysterious illness. Usagi is very worried, she holds his hand and with tears in her eyes she promises him that she will heal him and the world. Indeed she can destroy the Dead Moon Circus together with Sailorchibimoon and Mamoru recovers.
But Galaxia frees Neherenia who destroys her own black dream mirror. One of its shards gets into Mamoru's eye and he begins to behave strangely. Now he is aggressive and unrestrained. Usagi cannot understand why doesn't want to see her but stares into a mirror all the time. When Neherenia appears and Sailormoon cannot stop her from pulling Mamoru into the mirror she is desperate. Nevertheless she follows Neherenia although she knows that is a trap. In Neherenia's world of nightmares she is willing to sacrifice her life in order to free Mamoru from Neherenia's evil spell. Finally her love and compassion make him cry and the shard comes out of his eye. The nightmare is over.
Shortly afterwards Mamoru is going to study in America for one year. They say good bye at the airport. Mamoru gives her an engagement ring, they kiss and then he has to leave. When his plane flies above the clouds Galaxia attacks it with a bright flash of light. As Usagi has promised him she writes him every day and she misses him very much. She doesn't respond to Seiya's advances. Usagi even calls at his apartment just to hear his voice by listening to his answering machine. SailorTinNyanko is after Usagi's star seed, she traps her on the roof of the Juuban High School. Usagi transforms into Eternal Sailormoon and dodges. TinNyanko might have been successful if there were not a single red rose which distracts her. For one moment Sailormoon thinks that Tuxedo Kamen has come to her aid, but then she realizes that her rescuer is Seiya. After TinNyanko has fled Sailormoon breaks down and starts to cry because she thinks that she can't stand it anymore without Mamoru.
During the final confrontation with Galaxia the golden senshi shows Sailormoon her star seed collection. Sailormoon spots a golden shining crystal among many others. Galaxia tells her that this crystal allows her to control the earth, Sailormoon realizes that this must have been Mamoru's star seed and she begins to cry desperately. Galaxia's flashback shows how Tuxedo Kamen dies and he fades away calling Usagi's name.
But finally Chaos is defeated and all the senshi appear again. So does Endymion/ Mamoru. Serenity/Usagi is very happy, she flies over to him and he hugs her.
Later after the StarLights have returned to their planet Usagi and Mamoru are standing on a bridge. Usagi asks him if he really loves her and how much. Mamoru answers that he is always filled with energy when he is with her. They hold each other and kiss in front of a full moon.

The End