저 하늘에도 슬픔이(1965) / Sorrow Even Up in Heaven (Jeo Haneul-edo Seulpeum-i)

A fourth grader in Daegu takes over raising his younger siblings after his father gambles away the rent and his mother leaves, selling gum and shining shoes to keep them fed. His teacher discovers the diary he has been keeping through all of it and gets it published, which is what finally brings his parents home.

Why it's free: Free on the Korean Film Archive's own channel; the national archive holds and restores the prints it publishes.