Book Girl and the Wayfarer's Lamentation (light novel)

Tohko will be graduating soon. Although that thought makes him sad, when he spends New Year's with Kotobuki, Konoha feels the distance between them closing ever so slightly. However, when he hears that Kotobuki has been suddenly hospitalized and goes to visit her, he is reunited with a girl he never for a moment forgot! A girl who smiles exactly like she used to. However, Konoha's bonds with those around him begin to creak loudly, and she is at the center of it all. What exactly is the trut...