Letters from Kanai Nirai (2005)

Fuki who lives with her grandfather Shoei in Taketomi Island, Okinawa, dreams of becoming a photographer. In her childhood, her mother Masami left Fuki to live in Tokyo. Although Masami has not come back, Fuki receives birthday cards from Masami every year on her birthday. On Fuki's fourteenth birthday, Masami promises to confess everything when Fuki becomes 20 years old. After her graduation from high school, Fuki moves to Tokyo to work as a camera assistant. Fuki starts off her hectic life in Tokyo, and soon, her nineteenth birthday comes. As usual, she receives a birthday card from Masami. A year later...

Unfortunately the movie Letters from Kanai Nirai is not yet available on HBO Max.