One thousand years ago, there was a man named Endmyion - and he was the Crown Prince of the Earth. Beautiful, compassionate, vibrant and strong. He fell in love, as all men do, but his object was the beautiful Moon Princess, Selenity. Below, from the manga, is everything Usagi/Selenity and her former mother, the once Queen of the Moon Kingdom Selenity say about our Prince.
From Manga Volume 2
Tuxedo Kamen has just saved Usagi from a fatal blast from Kunzite (Malachite) but at the cost of his life. His head lays on Sailor Moon's lap. And he realizes he is Endymion - born again to be with his Princess, Selenity/Usagi. He dies. Tears stream down Usagi's face as she remembers....
Usagi holds Mamoru's head. She is now sitting in a flowing white dress. She takes out her moon watch. "Tuxedo Kamen's broken pocket watch..." she thinks as tears stream from her eyes. "It's starting to go in the opposite direction. Time's going backwards... I feel the memory of the past. It's so sad..."
"I remember," Usagi thinks. "Tuxedo Kamen... I love you, Endymion...
"My memory is coming back quickly. I'm drawn into your deep eyes. The same color as your blue planet. The star that hides hopes and dreams. Back then, I loved to watch that planet from the moon. And on that planet... The highest ranking royal prince. The strongest, most beautiful person. Endymion. I wanted to see you. Sometimes, I went to Earth to be with you, Endymion. But, we couldn't meet like that. Why? The people of the moon and Earth couldn't be together... We weren't supposed to love one another... But, it was too late."
*FLASH BACK* On the moon...
"Destroy the Moon Kingdom!" the woman calls (It is Beryl). "Bring me the Mystical Silver Crystal!" She turns. "Prince! Have you betrayed the earth!? This is all for our prosperity!"
"Stop!" Endymion calls. "You must stop! This is a useless fight!"
The woman raises her sword above her head. A gaseous entity smiles behind her (Metallia). She brings it down. Selenity screams as the blade cuts through Endymion.
*END FLASH BACK*
"Answer me!" Usagi pleads. "Open your eyes!" Tears streak down her face.
"I remember," she thinks. "We were born here, and met again. Is this our destiny, Endymion?"
"Tuxedo Kamen!!" she cries. "I can't do anything... I love you. You're the only one..."
In Manga Volume 3 we learn from the former Queen Selenity what happened on the Moon Kingdom to the Prince and Princess.
Usagi thinks of the past as she listens to Queen Selenity.
"When the Moon Castle was beautiful," the queen says. "The winds blowing inside the dome... But, Princess Selenity, you longed for the real wind of nature. You often went to Earth. And then, you found love."
"Yes..." Usagi thinks. "I wanted to be with him. The senshi were all watching me because I went to Earth so often."
"We were born on the moon," says Queen Selenity. "Our lives were long. The holy stone, the Mystical Silver Crystal, was handed down through generations. We removed the negative influences on Earth. We watched to make sure it evolved in a positive direction. One year... The sun's activity was too much. That abnormal sun created a terrible creature. It crept to Earth before we noticed it. It tried to take over Earth for itself. That creature... It was your enemy, a demon."
"I watched the huge power carried in the Mystical Silver Crystal," she continues. "That was how we lived long lives. The creature wanted the power. It took advantage of the humans. It manipulated people. Then it came to the moon. Only the young, aggressive prince of the Earth Kingdom, Endymion, tried to stop it. He was too late. He died defending you. You were so overcome with sorrow... You killed yourself."
We learn that Metallia, the evil gaseous entity had entered the hearts of men and women on Earth, causing strife and anger and hatred to abound. And she made Beryl - a common peasant woman - her vessel. Beryl was a woman who wanted power, greedy she wanted everything. Including the Prince Endymion. Below is a picture of her looking on as Endymion and Selenity embrace. Metallia and Beryl caused enmity between the Earth people and the Moon Kingdom. Even infiltrating Prince Endymion's personal guards - the four Generals.
In Manga Volume 3, as Beryl dies from Minako/Sailor Venus' puncturing her stomach with the Holy Blade of the Moon, Beryl says:
Minako clutches the sword and charges.
The sword pierces Beryl through the stomach and begins to glow. She screams as blood flows out of her wound.
"The sword!?" Minako thinks. "That light..." "I finally had you..." thinks Beryl. "Prince Endymion..."
The young Beryl watches from afar as Endymion and Selenity embrace.
"I've always been watching you." Her face contorts, her body begins to disintegrate. "Always." Beryl's tiara drops to the floor.
Funny. Although Beryl seem to be obsessed in love with Endymion she killed him in the past, and in the present used him as a puppet when his soul was dead but reviving his body.
When Endymion died in the past, Selenity had one last wish as death took her over.
From Manga Volume 3
"Endymion... Next time, we will be reborn on the same planet, and we will be happy. Mystical Silver Crystal entrusted to me... Please, search for us together... Embrace me softly... Protect us, and next time, make us happy..."
And so her wish was granted. There is more to learn of Prince Endymion - that of his Four Generals and his royal birthright under the Golden Kingdom, Earth's hidden kingdom, Elysion.