"Watashi ga Inakutemo Shiawase ni Natte Kudasai" Nante, Fuzakenna.

Synopsis

As I was spending my student days alongside my beloved girlfriend, one day, she suddenly said goodbye to me. After becoming a shadow of my former self, I learned that she died after struggling with an illness. The diary I received from her family was filled with her happy memories with me. (Source: Kadokawa, translated)