From beginning to end, I watched the entire show while high. I wasn't really sure until the last episode whether or not the main character was completely insane, and by proxy I started to question my own sanity and perspectives on things. The whole show gave me the impression that it was meant to be an allegory for mental illness, and it sent me on a philosophical, psychological and psychoanalytical roller coaster the likes of which I haven't had from any other audiovisual media. I thoroughly enjoyed the experience and I feel confident in recommending this anime. 10/10, do watch.
