Tobenai Chou to Sora no Shachi

Tobenai Chou to Sora no Shachi (飛べない蝶と空の鯱, lit. "Wounded Butterfly and Orca of the Sky") is a light novel series by Fuminori Teshima with illustrations by Saki Ukai.

Plot
"It's a promise. We will fly together, until the farthest end of the sky."

In a drifting world, where islands are floating above mists and where monsters are swimming inside those mystic mists unfolds the story of Will, an "Armed Postman" whose job is to deliver peoples desires and emotions contained in an "Envelope," and Jessica, a mysterious girl.

Will is bad at reading the winds while Jessica is afraid of flying due to a trauma in the past. These two people who cannot complement each other and cannot fly have the same dream which others wouldn't think of: to challenge the mist of death and find out what is at the farthest end of the sky. A refreshing fantasy adventure of a two-seated "Winged Ship," flying above the clouds.