From the Silver Millenium, Usagi was destined to be a ruler. The manga and anime both reveal that she was following in the steps of her mother. Yet, before her role could be fulfilled, Queen Beryl and Metallia unleashed their minions and, in the process, took the young Princess' life.

Reborn on earth as Usagi, she learns of her past life, as Princess Selenity of the Moon Kingdom, and is called to defeat Beryl and Metallia once and for all. She becomes Sailor Moon, champion of love and justice and defeats the evil forces. She wishes now to only liein peace with her Mamochan and her friends (in the anime they all lose their memories but in the manga, they never do).

But our lovely Princess' tale does not end here. We learn of a little girl from the future, who is revealed to be the future daughter of Usagi, and her true love, Mamoru. The little girl's name is Chibi Usa (or Rini to NA dub watchres). We learn that she came back in time to find Sailor Moon and get the Silver Imperium Crystal, in order to help her mother, Neo-Queen Selenity. This Neo-Queen is Usagi's future self in the 30th Century. In the manga, she rose to power age 22, giving birth to Chibi Usa, and according to the anime, became queen when she saved the earth from a frozen sleep with the crystal, making the earth a utopia.

Some people of the earth rebelled against her rulership, and were sent to a far corner of the universe where Nemisis (Wiseman) turned their hearts evil. They came and attacked the utopia on earth - known as Crystal Tokyo. The Queen was saved by being protected in a crystal case, but could not come out. Chibi Usa and Usagi (as Sailor Moon) defeat Wiseman in the battle that ensues. Usagi turns into Neo Queen Serenity and with double the power of the crystals, defeats Wiseman (anime). In the manga, she never changes into Neo-Queen but is there as herself and it is through her future self's help that she is able to save the world.

Because of her role as a leader/Princess/Queen, Usagi must take on GREAT feats to conquer evil. The challenges and responsibilities Usagi faces from her many royal lives, force her to mature faster than most females her age. She is the most powerful senshi, becomes very wise, and earns her role as Neo-Queen Selenity. She has the weight of the world on her shoulders and that is tough for any 14-16 year old to come to grips with.