雪代 すずの

Suzuno is a mysterious girl who claims she is a spirit not visible to human eyes. She’s quite childish overall but can be mature at times. Like Sakurako, she is soft-spoken. She also has a weak body and is clumsy. 

From url=http://en.wikipedia.org/wiki/Flyable_Heart, Calamitous Intent's review, and Liemyx's review