Her Blue Sky - Alternative Melodies (Light Novel)

is the light novel spin-off of Tatsuyuki Nagi's 2018 animated film of the same name. It was written by Saginomiya Misaki and Illustrated by Chouheiwa Busters. It was released under the Dengeki Bunko Imprint in October 2019.

Synopsis
Taking the world with music-The boy "Shinno" who has such a dream wakes up in the future 13 years after "that day" that should have come to Tokyo for some reason- "The second first love that connects the past and the present" A spin-off that draws the story from another perspective.

(source: Dengeki Bunko Official Website - Translated)