Hatanaka Kosaku, an aspiring boxer with a powerful knockout punch, struggles with a lack of discipline in his diet, often indulging in greasy hamburgers before fights. This habit forces him to compete in heavier weight classes, and when he inevitably vomits from a blow to his abdomen, he faces defeat and humiliation. Battling his inner demons, he crosses paths with Sister Angela, a young nun-in-training at a nearby convent. Despite her efforts to assist Hatanaka, his presence seems to pose challenges to her own path towards becoming a nun.