Houkago no Tinker Bell

Based on a story from the After School Series line of light novels. Kenichi Akizuki and Misako Watanabe work together to solve the mysterious disappearance of their classmate Ryouko Miyazaki. The only clue left by the kidnapper is signed Koushin Okazaki, her late classmate who'd committed suicide to preserve his youth and become like Peter Pan.