Sailor Venus is the "5th" sailor guardian. However Sailor Venus was awakened as a Sailor Guardian by a white cat named Artemis way before Sailor Moon and the other soldiers who were awakened by Luna. Her backstory traces back to CODE name sailor V, a manga series Naoko Takeuchi wrote before sailor moon. Her normal name is Minako Aino meaning the Goddess of Love. Before She was Sailor Venus, She was Sailor V. Minako's character changes a whole lot through out the 5 seasons of the show. Her personality is a bit bubbly like usagi's and is a bit boy crazy.
Venus Power, MAKE UP!
For love and beauty, I am the pretty guardian in a sailor suit, Sailor Venus! In the name of Venus, I will give you divine punishment of love!