I know that this is absolutely not the case - but the more I see Kurobe sneaking into the chapters, the more I get the feeling that "she knows about the secret".
Which, for obvious reasons, it isn't - she is clearly a side character that runs the role of being the attention grabber, a complete opposite of Sora. Yet she is also being set up as the rival for Sora's affections (mostly because she's observant enough to realize he does care under that facade), and is definitely a more important and developed character than the other side characters (girl with pigtails) and Misogawa.