This manga is absolutely my favourite of all times, no other manga has ever made me feel like houseki no kuni has made me feel. The feelings of dread and anxiety as I read a new chapter, and the glimmers of hope that were snuffed whenever I saw Phos going on with their journey of self destruction could never be replicated by anything I'll probably ever read. This is a tale of suffering for both the protagonist and the reader, but it is also a tale of hope and compassion too. Please give it a try if you don't find yourself in a spot where tragedy will upset you too much.
Houseki no Kuni