First things first, I have no idea what KM-KKS stands for, but I certainly know what a Tombow Mono pencil is...
I first heard about these hard to find, mainly Japanese market versions of the Mono on The Erasable Podcast when they had the amazing Caroline Weaver of CW Pencil Enterprise on (also where I bought these so please go look at her store). She had found these pencils in her recent travels to Japan and kindly brought some home to sell in her shop. I quickly scooped up a half dozen of them as they looked good and sounded awesome.
The more common Tombow Mono 100 is sort of the "tuxedo" of pencils with black and white paint and a gold ring around the end cap. Super sharp and one of my favorite pencils.
The KM-KKS 4B isn't quite as formal looking, but is a stunner too. The overall scheme is of a nice deep blue, white band with "MONO" in big black letters, silver stamping (all in Japanese mostly), and finished off with a bright yellow end plug.
Sharpening has been good with the core nicely centered and the point hasn't broken on me yet. The first thing I noticed was that it was extremely soft to write with. Being a 4B I didn't expect anything less, but after only about 25 or 30 words I was already itching to sharpen again.
Probably not the best for writing a novel with, but it is such a pleasant experience.
I mentioned the yellow end plug which polishes off he pencil nicely. Personally, I've mentioned it before, but I appreciate a pencil without an eraser more. It is cleaner looking. From what Caroline mentioned on the podcast, erasers on pencils do seem to be more of something done for the American market. Interesting....
As far as erasing goes, I tried to go your standard rubber eraser on the end of another pencil and it left a pretty strong amount of graphite in the page. I've been using Doane Paper large writing pads which have a pretty porous paper (but are awesome for pencils), so the 4B in addition to that could be part of it.
As I mentioned, Caroline has these in stock so definitely check her site out if you were wanting to give them a go. If they had a 2B (or B) readily available I'd be scooping some of those up too...