Zzz, got beaten to it, have a wiki instead:
Voiced by: Misato Fukuen (Japanese), Brina Palencia (English)
A genetically engineered bio-weapon, she uses nanotechnology to transform her body. Raised like a lab rat, Sven treats her like a real person and opens up her world. She tends to follow Sven, and since she and Train are so close, treats him as her rival as a Sweeper (although more so for Sven's attention). Eve later looks up to Sven as her father. She is often called "princess" by Train. She also has photographic memory. In nearly every episode, she is seen reading a new book. It becomes a sort of gag in early episodes as she read that putting bells on bad cats will make them good, thus forcing one around the neck of Train.