She had a much shorter appearance in the manag than she did in the Anime.
In the Manga she still dressed like a 20's gangster, pinstripes and stuff. It never says were she came from, but she had the starseed of Sailor Chuu that made mouse herself a sailor. The other scouts were just surprised that there were sailor scouts out of our solar system.
Iron Mouse sensed that Starlights at a concert and attacked them with 'Galatica Crunch'. The Senshi tried to attack her, but Mouse's bracelets absorbed their attacks. But Sailor Star Healers 'Star Sensitive Inferno' finished Mouse off.
~Back to the Iron Mouse Shrine~