Iriya no Sora, UFO no Natsu

is a Japanese light novel series written by Mizuhito Akiyama and Hatoto Akiyama (Vol 1 - 2), with illustrations by Eeji Komatsu. The series began publication on October 10, 2001 by ASCII Media Works under their Dengeki Bunko publishing imprint.

Synopsis
Asaba Naoyuki is an ordinary high school student. As a member of his school's press club, he's just spent the summer camping outside the local military base, in hopes of seeing the UFOs that are secretly kept there, according to local legend. Returning to school, he meets a strange girl, Iriya Kana, and gradually comes to realize that she is more than merely strange - and that a dark secret lies beneath the world that he knows.

Iriya no Sora, UFO no Natsu
An anime adaptation of the novel aired as an 6-episode OVA series between February 25, 2005 and June 29, 2005.