I looked through the Dorohedoro Sketchbook, and though I can't read most of it, I did recognize something on one of the pages. In a page written for volume 5 labeled "2003 10 16," in the lower left corner, there is a list of four bands - High on Fire, Neurosis, 27 and Amber Asylum. Of these four, three had recently (at the time of writing, late 2003) released on Relapse, a famous metal label. Neurosis in particular are notable for essentially creating the atmospheric sludge genre that one of my favorite bands, YOB, now inhabits.
Unfortunately I cannot be certain that these bands are listed for Kaiman's benefit here. As far as Google Translate can tell me, the text above says "Hayashida ball," which I don't understand. (You might have to click on the image to show the bottom of it)
If anyone can provide further insight I would be very happy. It looks like it might be a top 10 list where the rest would be on a different page, but I cannot find the rest of the bands anywhere.