Seishun Buta Yarou (Novel)

Synopsis

From Yen Press: Bunny girls do not live in libraries. This is simply common sense. And yet, that’s exactly where Sakuta finds one in the wild. More bewildering is who the bunny girl is: Mai Sakurajima, a girl one year older than Sakuta, famous at their school for her acting career even though she’s currently on break. To top it all off, it seems like no one else in the library can see Mai at all, no matter what she does or wears. Wanting to find out more about this mystery and maybe get a little closer to this beautiful upperclassman in the process, Sakuta launches an investigation to discover why an unforgettable bunny girl keeps becoming totally invisible.

Synopsis & details from MangaUpdates