Kugutsu Sorami

Summoned for a role of a victim by the Master of Tokyo Babel's first layer. Setsuna rescues her from the pangs of death.

Lacking memories since her arrival at the floating city, with no idea of who she should turn to or where she should go, Sorami ends up joining forces with Setsuna. She displays naivete of staggering proportions.

The fact that she swiftly and easily accepts the existence of angels, demons, as well as the reality of her amnesia and that of an impending world-wide cataclysm stands testament to a considerable amount of backbone on her part. ...No rigid beliefs tie her down, which, in turn, enables her to be quite flexible and open-minded in dealing with people from all walks of life.

In better times, she could've had the world under her heel as a superstar idol... or so Lilith asserts.

Spoiler

Her real name is Eve because she was created to serve the role as the "Eve" of the future. She is also referred to as #13, because she was the thirteenth person of the future to be created.