In terms of canon + popular consensus, the only subtext Koromo is ever involved with is with her and Fujita, I think (kinda awkward on account of the age gap, not to mention being kind of one-sided so it doesn't get much serious play). The standard Hajime x Touka subtext is also present in this work. I agree that the focus of the doujin is kinda undeniably not yuri so I would be for the removal of the tag.
All that aside, though--shit, that was seriously cute. Aside from doing really great stuff with the characters, it makes me recall the excitement which followed the first anime season. Thanks for the bump!