A song drama based on the autobiographical song "The sun is laughing" by composer Endo Minoru. It tells the story of a young man who moves to Tokyo with a big dream of becoming a composer, and despite the unfamiliar city life, sticks to his original intentions with the gentle encouragement of his young wife, and takes the music world by storm.

Bungo is released from prison to find his son Kenichi in the care of strangers. Teruko, the woman originally looking after the boy, was forced to leave town and sell herself into prostitution. Bungo and Kenichi, in their search for Teruko, arrive in a new place and find work running a peddling stall for the upright Tatsumaki family. However, the drifting father and son soon find themselves caught up in a struggle for territory. Boss Negishi, the head of the yakuza family responsible for the death of the former Tatsumaki leader, will stop at nothing to take over the marketplace. Sickened by the injustice, Bungo takes on the rival boss knowing it might cost him his newly acquired freedom..

Bungo becomes a single parent when his wife leaves him because of his drinking and gambling. Deciding to quit his vices, he works menial jobs, drifting from city to city. However, not completely losing his gambling tastes, he became a hunted man and must escape to Tokyo after he was found cheating at dice. Bungo and his son Kenichi comes upon the Kizaki Family in Asakusa, where more troubles are awaiting them...

Bungo, fulfilling his duty as a yakuza, kills a man from a rival gang. Since then, he has escaped the clan's vengeance by staying on the road with his son Kenichi. Tired of running, the two settle in a mountain town. Bungo finds work as a lumberjack for the Iwasaki family and Kenichi becomes a student at the local elementary school. Regrettably, their good fortune doesn't last. The yakuza boss, Tomitaka, wants control of the town's lumber and is willing to destroy the Iwasaki to get it. Natsue, Kenichi's estranged no-good mother, returns wanting to take part in the boy's upbringing. And shortly thereafter, a mysterious stranger arrives in town to lay claim on Bungo's life...