Krugger said: Isn't the naginata a polearm, unless the artist says other wise I think that is a katana at least. Never seen Momiji with a polearm before
A naginata is basically a sword polearm, it has a sword-like guard on it. the grip looks a bit long to be a katana, though from the string tied at the end it could actually be a Odachi or Nodachi
I don't think that's a naginata. Look at the rope ornament at the end of the grip, you can tell that the grip is too short to be a naginata. I think it's a nagamaki, an uncommon kind of japanese sword. The grip of the nagamaki is about the same length as the blade. Longer, and it would be a naginata, but this is most likely a nagamaki.