Based on a true story and was adapted from the autobiographical novel "8 Nen Goshi no Hanayome Kimi no Me ga Sametanara" by Hisashi and Mai Nakahara and adapted into screen by Yoshikazu Okada (Kencho Omotenashi Ka), the film is directed by Takahisa Zeze (Moon Child, Heaven's Story), and is set for a December 16 release.
[Additional info from AsianWiki]