It really was very difficult to read, their characters suffered a lot in each scene to the point of thinking that more people could die in the next chapter.
The careful and cute drawing makes us assume that we are reading a beautiful story, but the dialogues and scenes are quite adult. I dont consider myself sensitive but this work gave me the nervousness that you expect from a psychological thiller with a good story.
My recommendation is that you read it knowing that there is a lot of crazy and shocking scenes that will make you nervous, although you will have good character development complementing the most mundane chapters.