I know a lot of people end up searching for the Kyureido kk-002 cheek brush and I didn't exactly know where to put this...
But there is a Japanese ebay seller who has the kk-002 brush in stock and for sale! It is more expensive than the website but just letting people know that there are other options out there depending on preference.
Ebayer is 2005yoshiki (apparently you can also do monthly payments for 6 months too.
The seller has other Kyureido brushes as well as mizhuo and tanseido brushes.