Hi mate,
Kawasaki will sell you a wrench that neatly fits over the top of the filter like a cap for about $15-20. You plug your 1/2" drive ratchet into this and Bob's your uncle.
Honda have one which also fits. This one has a nut welded on the top of it and you use an open-ender to do the same thing (a ratchet open-ender is really good). Having had a ZZR600 before the Hornet I now have one of each as the ZZR one fits, but you can't get a 1/2" ratchet under the pipes of a Hornet (they're a crappy design, no thought taken in the install at all).
A budget method is to punch a hole through it with a screwdriver. A warning though, I tried this and ended up with the filter in two pieces

. I then had to use the screwdriver as a chisel and tap it off with a hammer.
If you find you can't find the filter at your local dealer drop me a PM and I'll mail you my old ZZR one.
thks, MIck
