Hello, today we have the final chapter of Volume 11 for you. Edit: Volume 11 batch link added.
Volume 11 Special 2
Kazuya and Kiriha go to the school at night to deal with an abberation. This chapter was a promotional one-off that ran in a magazine while Tsugumomo was still a web comic. The afterword at the end of the volume is also included.
Volume 11 Complete
And here’s the complete volume.