a1b2 said: P.N. is Pen Name in this case. Kafuka isn't her real name, it's the pseudonym she is given in the series, or so I read somewhere.
"Kafuka Fuura is a pen name, taken from the name of author Franz Kafka, and is quite at odds with her sunny attitude. Her real name has not been officially revealed; however, she was referred to as "An-chan" in a flashback, and the surname "Akagi" appears in the attendance book, leading fans to speculate that her real name is An Akagi (赤木 杏, Akagi An). In another flashback, she had a name tag that said "An" on it. This would parallel Nozomu's comment in the first chapter about her personality resembling Anne of Green Gables (赤毛のアン, Akage no An)." Quoted from Wikipedia, and speculatively speaking.