hello, new to the forum, but didn't see anything in particular about the kuretake pen(s). I found one fountain and one disposable online and wonder if anyone has used one or the other. The fountain pen is rather dear at more than USD30.00 at Blicks and a disposable one for quite a bit less but in Great Britain (only).
At 2.5 years later, you probably are not viewing this thread anymore, but I am curious as to what the alternative brush pen that you found was. My guess is the Pentel Pocket brush pen, which is quite nice.