Also dumping Shinozaki-san chapter 30.
From what I found, it's still being translated.
Page 8 was missing in the rar file.
All a doujin is is a self-published work; plenty of authors have released standalone chapters at Comiket and the like. Kase-san springs to mind.
Porn or crazy setups or other stuff people often associate with doujinshi, less so.