Yoko the Cherry Blossom(2015)

Overview:

In 1940, Masaaki Takaoka works as a teacher in the agricultural division at a youth training institute. Although Japan’s defeat seems imminent, all of Masaaki’s students are drafted in a futile last-ditch effort. In an attempt to give the young men some hope, he makes everyone promise that they will all meet again under the cherry blossoms upon their safe return. Consumed by sadness over the fate of his students, Masaaki devotes the next 30 years of his life to develop a new species of cherry blossoms that could thrive in any climate in remembrance of his students.