Katajanmarja said: "Source: bkub" gives the impression that KimidoriSan got this as a preview by email from the artist.
Well, this (as well as the Rinnosuke pages) is from one of the previews he sends to doujin sellers interested in carrying his stuff. Once the doujins come out, he puts them on his site in the large scans we're normally familiar with.
Basically, there'll be a full-size version in a couple of weeks.