Deadly Class 1: Akademie der tödlichen Künste

The gritty depiction really immerses the reader, but I'm curious if this was based on real schools or purely fictional. What inspired this intense setting?

The story makes it hard to tell who the 'bad guys' really are. Did others find themselves sympathizing with characters who do terrible things?

The visual storytelling adds so much to the mood, but I wonder if the author considered other formats or if comics were the only way to convey this tone.