Let's start off with a familiar face.

A stylized depiction of Amami Haruka with her face formed by the characters ののワ (hiragana no no and katakana wa = nonowa). Sort of like this:
の の
ワ
or this:
のヮの
When she appears together with the regular Haruka, it might be a case of dual persona.
EDIT: Information from the original post on the old forums rescued. Thanks to Drunken Watermelon.
Actually, it isn't certain what Nonowa actually is. The only one clear fact is that she is one of various characters derived from Haruka Amami. She was suddenly born from the forum "Tokachi-Gumi" in November 2007.

It has been known that Haruka often looks upwards to the left (or her right) quite a lot. A member of the forum invented an ASCII art emphasizing the feature. This simple text art, a combination of 3 Japanese phonograms, "のヮの," could completely express Haruka looking aside in manga/anime style.

Obviously, in the early days of the meme, "Nonowa" was just an icon indicating Haruka herself. However, as "Nonowa" spread for relative groups, an original personality was given to it. This was the birth of the character Nonowa. She is portrayed as a small living organism, with nothing on except ribbons on her hair, has a "chibi" figure, and, similar to the mythical sprite creatures, can be very mischievous, quick-tempered and troublesome. Similarities between Nonowa-san and deformed characters of other girls in The Idolm@ster, called "creatures" (eg. The Yayoi Creature) has also been pointed out.

Currently, Nonowa-san is recognized as a independent character from Haruka Amami. The character has been illustrated in many illustrations, even appearing in several movies. However, it is is very difficult to figure out who or what Nonowa is, because various works illustrate her in a different personality and profile. Regardless, its lovely appearance and silly behavior must make watchers happy. If you hope to become familiar with her, it is quite easy. By just writing down three Japanese characters, "のヮの," you can see her wherever you are.
Based upon information from
http://idolmaster.tdiary.net/20080717.html#p06I've cleaned up the translation for easier reading.
Feel free to add anything about the other Idol Creatures (ie:Yayoi Creature, Miki Kuri, Chihacula, etc).
