Jeffery Tan’s review published on Letterboxd:
This film is not perfect. From a manga that is 7 volumes long, it is simply impossible to condense every plot and characters' development into one 2-hours feature film. Numerous details are bound to be lost and cut down, which is why the plot does feel incoherent at times and some side characters aren't really established that well in the film. However, I believe that this is one of the cases where those obvious flaws can be overlooked and forgiven, just for how important and brilliant the central themes are.
This is a film that understands self-loathing and the behaviors of excessive self-awareness. Our main character is not the kind of protagonist who can convey his thoughts perfectly or act rightly in any given situation. He is a broken person who perceived himself as lower than any other human beings on Earth, and thinks that he doesn't deserve to live. His values of existence are buried under the overwhelming sense of doubts that he repeatedly placed on himself. For every iteration of intense self-deprecating, the words become silent, the intentions become unimportant, and the ego is reduced to zero in the end. He rejects his own identities, afraid to think or even act for himself because that's a selfish thing to do and he isn't ready to show his own flaws in front of other people yet. So, he hides away from the crowd, feared to be identified, feared to meet expectations, feared to be himself, and admits that everything is his own fault for not being a decent human being yet. This film portrays those feelings so genuinely that it's hard not to relate to some part of it if you perhaps have experienced insecurities before.
I cried so hard watching the first 30 minutes of the movie because of how real everything feels and also realizing that it was the beginning of the mind descent for the protagonists, it was heartbreaking. Well, I guess it's time for me to read the manga again.