One day, I – a high schooler – found a paperback in the hospital. The “Disease Coexistence Journal” was its title. It was a diary that my classmate, Sakura Yamauchi, had written in secret. Inside, it was written that due to her pancreatic disease, her days were numbered. And thus, I coincidentally went from Just-a-Classmate to a Secret-Knowing-Classmate. It was as if I were being drawn to her, who was my polar opposite. However, the world presented the girl that was already suffering from an illness with an equally cruel reality…

Type: Manga
Volumes: 2
Chapters: 10
Status: Finished
Published: Aug 25, 2016 to May 25, 2017
Genres: Drama, School life, Seinen, Slice of life, Tragedy,
Authors: Kirihara, Idumi (Art), Sumino, Yoru (Story)
Serialization: Monthly Action

Manga ini berdasarkan Light Novel populer dengan judul yang sama karangan Yoru Sumino-sensei, yang sudah memenangkan berbagai macam penghargaan , diantaranya :
“Bestsellers 2016 (Overall) by NIPPAN” – 4th Place

“Bestsellers 2016 (Paperback Fiction) by NIPPAN” – 1st Place

“Bestsellers 2016 (Overall) by TOHAN” – 5th Place

“Bestsellers 2016 (Literary Books) by TOHAN” – 1st Place

“Bookstore Grand Prix 2016” – 2nd Place

“DA VINCI BOOK OF THE YEAR 2015” – 2nd Place

“Bestsellers 2015 (Literary Books) by TOHAN” – 6th Place

Pada bulan May 2017, Light Novel ini sudah terjual lebih dari 1.2 juta kopi.