head of a household; business owner; proudly independent person
Modern figurative use: someone who is the master of their own domain, whether a home, a small business, or a personal sphere, with a sense of proud independence.
定年後は小さな店を開いて、一国一城の主として気ままに暮らしている。
After retirement, he opened a small shop and lives freely as the master of his own little domain.
彼は家
Historical literal meaning: a lord who ruled a single castle and its domain. Now used mainly in historical contexts or as the origin of the modern figurative sense.
At home, he is the lord of his own castle.
In the Warring States period, ruling a domain as the lord of a single castle was a mark of a daimyo.
城主 refers specifically to the lord of a castle, while 一国一城の主 emphasizes the independence and authority over a whole domain, often used figuratively today.
マイホームパパ is a family-oriented dad, whereas 一国一城の主 implies a more assertive, independent mastery over one's household or business.
Literally 'lord of one country and one castle'. Originates from the feudal era when a daimyo held a single castle and its territory. The modern figurative sense extends this to anyone who is the undisputed master of their own small domain.