Aihana Aoi

The childhood friend of Haruto Soraki. Appeared in Haruto's dreams speaking of a promise to see each other at a well 7 years later to see the Akitsu Carnations bloom. She had the mysterious disease LMD and is the second longest stayer at the hospital (after Haruto), making her the first to meet him there. As the character glossary suggests, her loved ones likely died before she was admitted to the hospital.