Seishitsu (正室) is the Japanese term of the Edo period for the official wife of high-ranking persons.
The tennō, kugyō (court officials), shōgun and daimyōs often had several wives to ensure the birth of an heir.
The seishitsu had a status above other wives, called sokushitsu (側室, concubine).
At the time, the main wife was called chakusai (嫡妻).
Succession disputes between sons of the official wife and concubines were a constant source of internal, often armed conflict within houses (O-Ie Sōdō).