The Tombow Mono KM-KKS Pencils are extremely hard to find outside of Japan and even in Japan, they remain the secret of artists and stationery cognoscenti.
The lead is 6B - black, extremely dark, rich and soft - and the pencils are highly recommended for art, illustration, shading and more.
USES: Great for illustration. 6B is softer and darker than 4B
SOURCE: Made in Japan