I initially stumbled upon this movie when researching the Japanese rock band by the same name, Dotsuitarunen (=Knockout). Apparently raking in several awards at the time of release, it wasn't until recently that a widely available version with fan-made subtitles resurfaced on YouTube*.
It's a bittersweet tale of a man who knows only one way to solve his problems: with his knuckles. After getting knocked out in a fight and making it out alive from a difficult brain surgery, star boxer Eiji Adachi (Hidekazu Akai, himself a pro boxer) decides to throw the towel and attempts to run hiw own gym.
Despite the help of another old ex-pro boxer, the mysterious and stuttering trainer Makio Sajima, they fail miserably albeit comically due to Eiji alienating his students through his hard-knocked teaching methods.
Troubled, but unable to imagine a life without boxing, Eiji decides to come back to boxing despite his head injury, as he proclaims "What else can I do? I know nothing but boxing."
After the obligatory Training Montage, the story culminates in a final fight between Eiji and one of his former soft-natured students. Just as the opening fight, it's another matter of life and death.
I have to admit, I haven't watched many boxing movies but I really liked this one. It has an endearing story, solid cinematography, great fight scenes, odd characters and lots of humorous moments that at times border on the surreal.