I'm so sorry to hear the author/artist passed away, and so very young at 28, too! He was a rare talent.
Weird thing about the manga itself - I'm having one of those Mandela Effect moments. I recently re-read this, and couldn't find a scene that I was so very sure was in the manga: we get to see the inside of Luna's bedroom, and one wall is entirely covered with candid photos of Sora from age 5 up to now, because she's been stalking him ever since grade school, when she was a chubby unattractive girl with glasses.
Am I thinking of a different manga?