Kosaku Hatanaka, a promising boxer trained under Coach Mukoda, was once the only professional athlete from their gym. However, his career has been marred by disappointment, largely because he repeatedly fails to make weight for his matches. After a humiliating incident in the ring that caused several scheduled fights to be canceled, Kosaku is warned that his next bout might be his last if he doesn't improve.
His situation seems dire when, breaking his strict diet, he convinces Sister Angela, a local trainee nun, to give him food. It looks inevitable that he will once again surpass the weight limit, potentially ending his boxing career. Realizing her unintentional role in his overeating, Sister Angela takes it upon herself to help him get back on track—even as Kosaku finds himself more drawn to her than to her spiritual advice.