Introduced as the “Second Generation Angeloid, Type Epsilon”, Chaos is the first major antagonist introduced after the Synapse. Ironically the most minute and child-like Angeloid, weighing 19 kilograms and being only 107 cm in height, she appears as a young child dressed in nun-like garments which can manipulate her appearance through elaborated illusions, mimicking someone dear to her victim in order to instill turmoil and confusion, as she did against Nymph by taking on the likeness of Tomoki. She lacks wings like other Angeloids, sporting a wicked array of bladed, almost organic-like appendages which act as an offensive weapon. Most eerie is however the strange obsession that Chaos has with love, having asked to Tomoki, Nymph, Astraea and Ikaros, often in an extremely creepy manner, what love is, to which Ikaros responded that love, for her, was a sensation of pain in her reactor, obviously in a figurative sense.
Chaos appeared first to torture Nymph, and then engaged both Ikaros, which initially bested through her illusions, and then Astraea. After sometimes she battled Ikaros again, though this time her opponent saw through her illusions and defeated her, sending Chaos into a deep abyssal chasm where she was temporarily incapacitated due to the great water pressure. While there, she wondered about Ikaros’ statement to what love means, coming to a dreadful conclusion: love equates to pain. Chaos was left in the abyss, dismembering and devouring fishes to - in her own words - grow bigger and show her “love” to everyone.
At the end of Sora no Otoshimono: Forte, she reappeared with a grown-up appearance to fight Ikaros, Nymph and Astraea, and was eventually defeated by them. She is currently living with Tomoki and co. .
In the manga, when she met Tomoki again, she developed a feeling similar to love, and decided to “go home” to the Synapse. Chaos was then thrown away by her master. Ultimately she got destroyed along with the evolved Astraea but was bought back to life again when Tomoki restored the whole world back.