I knew it would only be a matter of time before they announce it. It was announced on Barks earlier today that Kimi ga Kureta Natsu / 君がくれた夏 will be released as a single on March 18, 2015!
As I’ve said in my previous post on the song, the song is the theme song of the upcoming movie, Ashita ni Nareba / あしたになれば, which will be released on March 21, 2015, a few days after the single (the official site[jp] says something about February 14. Perhaps an early viewing?).
I expect the cover art to be revealed within the next few weeks. I’m very excited for this!