I think I read a review of this film, and it did not speak too well about it either.

Character development is very crucial in presenting the story of a film. I do not understand how some filmmakers just think they can just center on the protagonist and care less about any other character. The other characters are to be designed to support and give life to the protagonist because, in the end, everything can fall and crumble if the other characters are disregarded.

I do not see manga, but if I ever considered trying it out, I sure would not want to start with this one you have talked about. Well done.