Looking at Love and Death (2006)

Original title: 愛と死をみつめて

Based on a real-life novel by Kawano Minoru about a senior high school girl, Michiko (Miko) who contracted a terminal illness and the 400-plus letters she and her boyfriend Minoru (Mako) attending university wrote to each other over 3 years. Miko died at the age of 21 subsequently