Sailor Iron Mouse is the first of the Sailor Animamates to make an appearance. Her human alias in the anime is Chuuko Nezu, which is a playful pun. In Japanese, "Chuuko" and "Nezu" are both valid names, but "chuu" is the sound a mouse makes, and "nezu" can also mean "mouse." True to her name, Iron Mouse is very short, standing at least a foot shorter than her targets. According to Takeuchi's notes in the manga, she is supposed to be Chibiusa's height, though she appears slightly taller in the anime. She also has a fear of cats.
In the manga, Iron Mouse's presence is brief, spanning only a few pages. She appears in Act 43 at the Fantastic Music Hall during a joint concert featuring the Three Lights and Michiru Kaioh. She attacks with "Galactica Crunch" and is ultimately defeated by Sailor Star Healer. It is later revealed that Sailor Iron Mouse had killed the Senshi from her home planet, Sailor Chuu.
In the anime, Iron Mouse's personality is both childlike and intense. She tends to target famous or impressive individuals, seems to take pleasure in her work, and is openly terrified of Galaxia. She can teleport using a phone booth she summons and uses it to evade attacks as well. Sailor Iron Mouse serves as the antagonist for several episodes before being killed by Galaxia in episode 181 as punishment for failing to collect starseeds, even though she had uncovered Sailor Star Fighter's identity.
