Veteran scriptwriter Haruhiko Arai spent three decades trying to adapt Yuichi Takai's 1983 novel "Kono Kuni no Sora" ("This Country's Sky") for the screen — and the wait was worth it.

The film, about a 19-year-old girl's awakening to love and life in the closing days of World War II, has the dark honesty and erotic intensity found in Arai's best scripts, including the trio of acclaimed films he wrote for Ryuichi Hiroki: "Vibrator" (2003), "Yawarakai Seikatsu" ("It's Only Talk") (2005) and "Sayonara Kabukicho" ("Kabukicho Love Hotel") (2014).

But Arai, who has directed only one other film, also drew inspiration from "Watashi ga Ichiban Kirei Datta Toki" ("When I was at My Most Beautiful"), a 1958 poem by Noriko Ibaragi that his heroine, Satoko (Fumi Nikaido), reads over the closing credits. It is a key to understanding this character, who is mature beyond her years but has yet to taste much of life other than war's privations, restrictions and terrors.