Darien/Mamoru
Darien was orphaned in a terrible car crash. At the time he suffered from complete amnesia. He wasn't even sure if his name really was Darien. Because of this he grew up in an orphanage. He started working at the arcade where Serena liked to hang out with her friends. For some reason he was always picking on Serena. Not even knowing why himself he felt compelled to. He also dated Raye at one time. He suffered from black-outs. He also started having dreams about a Princess begging for his help. Because of these things and other circumstances he finally realized he was:
Tuxedo Mask
As Tuxedo mask, he fought to protect SailorMoon and the Scouts. He did eventually recover all his memories, and the fact that he too had another secret identity from the past:
Prince Darien
Long ago when he was Prince Darien of the Earth, he was in love with Princess Serena from the Moon Kingdoom. These feelings still remained. But then he was kidnapped and brain-washed by the evil minions of the Negaverse. Thanks to Sailormoon he was saved. After the defeat of Queen Beryl and the Negaverse his memories were again erased. But when evil arose again it was Darien's courageous soul that created another identity to protect Princess Serena:
The MoonLight-Knight
When the evil was once again repelled, he regained all his memories. But the biggest shock for Darien was the day they discovered that the mysterious little girl Reenie, was SailorMoon's future daughter!! They also found out that she was in fact his daughter too!!! And he was the future husband of Princess Serena:
Neo-King Endymion

Through all of this Darien's love remains strong and true for Princess Serena. As does his devotion to protecting not only SailorMoon and the Scouts but the Earth as well. His adventures with SailorMoon and the Scouts continued.