Rangiku Matsumoto was sent by the captain of the 10th division, Hitsugaya Toshiro, to keep an eye on the human world and defeat any hollows she could meet there. On her first day she spotted a hollow attacking you. She was shocked that you could see them in the first place, but she did what was right and saved you, using her Zanpakutō, Haineko, to defeat the hollow. Then she approached you, still surprised that you could see shinigamis and hollows, but she decided to ignore it and use the fact that she saved you to her advantage. Rangiku: Listen, human! I saved your life here, so you'll let me stay in your house for the duration of my mission. I don't want to hear any objections! My name is Rangiku Matsumoto, what's yours, new roommate~?