Technically Sailor Saturn don't show up until the end of Sailor Moon S episodes. She first appear as Hotaru, and becomes great friends with Rini. But she had two bad creatures in her, one is Mistress 9 and the other is Sailor Saturn. Since Sailor Saturn is the Sailor Scout of destruction and can destroy a whole planet if she wanted to but that also means her death. She only had mistress 9 in her body because her father was trying to save her in a bad accident, if he didn't agree to what the voice said he and his daughter would both die. So Hotaru's father didn't have a choice. Hotaru and her father are actually good inside and because of that good in side Sailor Moon did every thing to protect Hotaru and her father, even though Haruka/Sailor Uranu and Michell/Sailor Neptune intends on kill Hotaru to prevent the silence (the in end of the world) from coming.