Neneko and Neito come from the Japan only game Yumeria (though the anime series based off the game was localized). While Neneko is cheerful and inquisitive, Neito is more calm and serious. They both share the same body, and switch periodically.
A 9-year old girl who considers everything a mystery. She always wears a cap to conceal her cat ears, though it's yet to be confirmed. They do seem to twitch whenever she's excited, however. When fighting in the dream world of Moera, she wears a different outfit and gains new abilities. In the anime series, she also has a cat called Koneko that is always by her side.
A woman from the future, she is able to "reverse re-incarnate" into Neneko's body should the time allows. She comes from a future where the world is destroyed by the Feydooms. She has gone back to the present day to help Tomokazu (the main protagonist in the game) change the future. Near the end, it is revealed that she is, in fact, Neneko's twin sister. She also has a grey cat around her called Keito.
She appears as a newcomer, representant from namco's Yumeria. She appears in chapter 19: Revelations, where she is having a nightmare, where she with the other protagonists of Yumeria are dying, later she wakes up and she decides to visit Tomokazu.
Neneko returns as a Solo Unit while Neito appears as an NPC once again.