It sounds like it's similar to the Kodak Retina design; leaf shutter in body, then comes the lens; then some elements, then the aperture blades, then some more elements.
I need to preface the next with the fact that I've never worked on a Kowa lens.
Typically, the aperture blades are closer to the rear elements, but taking a lens apart from the rear usually involves springs and levers, so it is more difficult. So I will almost always go in from the front. The beauty ring (the ring with the lens info on it in the front) is usually screwed in, and needs either a spanner wrench or a rubber stopper (big enough to cover the ring) to unscrew it. After that, you can usually take out the elements or groups of elements to get down to the aperture assembly. Once you get to that, you can either use the electronics cleaner or lighter fluid to (hopefully) free up the blades. The other option is to remove the aperture assembly and clean each blade individually, but this will most likely require a (near) complete teardown of the lens.
Most of the time the lighter fluid/electronics cleaner gets the job done. It takes a whole lot of either, and quite a few cotton swabs to remove the oil/lube, and to completely clean the blades. Whatever fluid you use will get on the remaining lens elements, but doesn't hurt them (at least that I've ever noticed), and cleans up pretty easily.
This is probably a good lens to learn on, as they aren't very valuable.