A Google search of the text in this image led me to this page, identifying it as being from a doujin called ビアホール小岩井 ("Beer Hall Koiwai") and the author is wang-pac. I then searched for the doujin's title and the information on several sites (for example, Suruga-ya) confirmed that wang-pac is listed as the author and associated with the same doujin circle (Group Hinoran).
