This portrait was done in a 3.5*5.5 canson blue book. I started the sketch with a extra fine point fountain pen. This part of the sketch took roughly 5 minutes. I then added the light areas of shadow with gray ink in a Pentel pocket brush pen (PPBP). I added additional layers to create darker areas of shadow before switching over to a Kuretake #8 brush pen with black ink. After that I used sepia colored watercolor to color the background.
You can get a Kuretake #8 brush pen from Jetpens.com for about $13.50 it's a very nice brush pen, though much longer than the PPBP.