Oh what a SURPRISE, there's Wayang (wich i just watch recently on Jogja) inside the movie after about 1 hour 15 minutes. Well i ever heard about Wayang show on Japan but it's only on Indonesian Embassy i think, or maybe somewhere else? Well this is the preview of the original Taiyo Matsumoto comic version.
Oh right! the ending song is from ASIAN KUNG-FU GENERATION titled 或る街の群青. Kind of peculiar huh? here's the movie trailer;