I recommend "Letter No. 3654". This book meets your needs! The male protagonist was the female protagonist's university professor. In order to express her feelings, the female protagonist wrote many letters to the male protagonist, but the male protagonist did not receive them. Later, the female protagonist went crazy for various reasons. The story was very touching, giving people a lot of inspiration and inspiration. It was also very easy to immerse oneself in it. I hope you like this fairy's recommendation. Muah ~๐