It amuses me that neither Kase nor Yamada seem to be even tangentially aware of Aikawa on any level. Everybody else greeted Aikawa and Fukami, Kase only noticed Fukami, and pretty much all of Yamada's jealous worries have been directed at the roommate.
I kinda see why we didn't get a characters or chapter page this volume, it would have given away way too much!
Also, aren't we into volume 16 territory by now?