I do agree the story was not quite appealing, but I believe this movie was quite creative and very ambitious.
The original source is a novel by Osamu Dazai. A story about a man named Oba Yozo, a man that had lived a life of misery and was brought to ruins. The reality about the novel is that the entire story was basically Osamu Dazai's autobiography. His consciousness struggling to cope up with despair and questioning his own human self. The anime uses this story and twists it into a different setting. While completely twisting everything, they still stick with the elements from the novel.
If you all want to watch the movie, I highly suggest not to watch the movie just for the story, but see it as a work of art. Try to look through the emotions of the characters rather than their motives.
