Denpa teki na Kanojo

Denpa teki na Kanojo (電波的な彼女) is a Japanese light novel series by Kentarō Katayama, with illustrations by Yamato Yamamoto. In 2009, a two-episode OVA adaptation was exclusively bundled with the pre-order editions of Kure-nai DVD volumes 3 and 4. Kure-nai is another anime by the same author. Under the title Denpa Biyori (電波日和), the first story in the series won an honorable mention at the Super Dash Novel Rookie of the Year Awards in 2003. The Japanese term denpa originally referred to radio waves, but in slang usage it refers to people who perceive things sane people can't.

Plot
Jūzawa Jū is a delinquent high school boy who just wants to be left alone. One day, he is approached by Ochibana Ame, who claims that she knew him in a previous life, and now wants to serve him as his "knight." At first Jū wants nothing to do with Ame, but after a classmate is murdered, he accepts her help as he looks for the killer.