Before joining the other scouts in Japan, Minako lived in England with her parents. After an encounter with a white cat named Artemis, Minako learned that she was the bishoujo senshi Sailorvenus, Princess of Venus and defender of Earth.
Minako fought crime in England under the name of Sailor V. (It is debated on whether the "V" is short for Venus or Victory.) She was extremely popular, spawning her own video games, movies, comics, dolls, etc. Sailor V was known for catching the bad guys before the police, thus their (the police's) dislike of her.
One day, while on a mission, Sailor V and her two fellow crime-fighters Alan and Katrina were caught in an explosion. All of England thought that Sailor V was dead, including Alan and Katrina. Minako was deeply in love with Alan, but Alan loved Katrina...Minako was going to show herself to them, but then she saw the two kissing. She decided instead to leave England altogether.
Once in Japan (of course with Artemis), Minako met up with the other senshi. She saved them and Tuxedo Kamen from Zoicite and Kunzite using her Crescent Beam attack, still in the Sailor V disguise. She then revealed herself as Sailorvenus, and the (fake) Moon Princess. And thus the tale known as "Bishoujo Senshi Sailormoon" began, and if you don't know what happened in that tale, then you are really sad.