Usagi is shown as very clumsy, ditzy and airheaded, but also as very beautiful and deep. However, she's mostly just ditzy in the beginning of the series, you see her grow into a mature young women throughout the show. Usagi will die for any cause and always protect her loved ones. Though the show ended in Sailor Moon Stars, basically I'm just doing some mixes up in here so just to make things fun...

Princess Serenity lived peacefully on the moon with her mother, Queen Serenity. There time of ruling was called Silver Millenium. Almost as body guards, four soldiers were there to protect her, each royalty of their own planet. There was Sailor Venus, who was the leader, Sailor Mercury, Sailor Mars, and Sailor Jupiter. Trouble started when the princess fell in love with Prince Endiymon (future Mamarou), who was from earth. Up until then, rarely no one would even talk to the earth people. Also the fact that which is was a problem that Their love was tested when Queen Beryl came to take over the Moon Kingdom. She killed everyone, along with the Sailor Senshi guards and when the time came she tried to take Prince Endiymon for herself. When he didn't agree she killed him, along with Princess Serenity who wanted to die with him. Queen Serenity watched all this happen, with people dying everyone to protect her Moon Kingdom. She sacrificed herself for everyone else to be reincarnated to future earth, which is our present. When Princess Serenity was reincarnated on earth, she was born as Usagi Tsukino / Sailormoon, along with the other sailor senshi who too were reincarnated. In present times of Tokyo, is Usagi Tsukino. She's a high school girl who goes to Juuban High. Her parents are Ikuko and Kenji, and she has a brother named Shingo. She also lives with Chibi-Usa (her future daughter) who is at first brainwashed into thinking she's Usagi's cousin. Usagi is the leader of the Sailor Senshi, who were her past guardians. In the future Usagi is Neo-Queen Serenity, who is queen of the earth in the 30th century, Crystal Tokyo. In the future she is married to Ediymon (present time Mamarou.) They have a daughter named Chibi-Usa. When Nemesis come to Crystal Tokyo and start turning everything to ice, the only place they cannot get to is the Crystal Palace. This is because the Sailor Senshi are using their power to not let anyone in. The only thing that can stop them is the ginzuishou, a special crystal looking thing. However, the The only thing that can stop them is the ginzuishou is no where to be found. So, Chibi-Usa is sent to the future to retrive the The only thing that can stop them is the ginzuishou and bring it back to stop Nemesis. When Chibi-Usa finally returns back to Crystal Tokyo, Neo-Queen Serenity is able to use her power to stop Nemesis.