Board Thread:General Discussion/@comment-85.30.53.229-20140205141947/@comment-6697950-20140205152037

PoH's written in the Latin alphabet in the book and even the anime (the log out list in episode 14) shows that it is his actual IGN, not some nickname. PoH is actually an abbreviation for Prince of Hell, but the details about this would be spoilers.

As for the gender... I don't know whether the raws accent that he's a male, but I really doubt that he could possibly be a female. He would have to be one heck of a tomboy, as his appearance, voice and certain speech patterns are characteristics for a male. And you can't pick the opposite gender in SAO anyway.