Taishin (person of high rank and income) refers to a person who has a high rank and a high stipend. It refers to a person from a high-ranked wealthy family.
From the Muromachi period to the Sengoku period (Japan), among Kokujin Ryoshu (local samurai lords), a feudal lord who was descended from a clan in the Kamakura period, possessed more than several Gun and had the power equivalent to Daimyo (Japanese feudal lord), was called Taishin. For example, Chikugo 15 castles.
In the Edo period, Hatamoto Yoriaiseki (a family rank of high-ranking Hatamoto, direct vassal of the shogun) who had more than 3000 koku (a unit of volume: rice 1-koku is 180.39 liter, lumber 1-koku is 0.278 cubic meter) as well as Hatamoto (direct retainers of the bakufu, which is a form of Japanese feudal government headed by a shogun) who had more than 2000 koku and managed to do Kaminanori (announcing as a provincial vice-governor), were called 'Taishin Hatamoto' (greater vassal).
Even after the Meiji period, 'Taishin' remained as a word referring to a high government official, a head of Zaibatsu (a financial clique or group, or company syndicate), and the peerage until the time of World War II in the Showa period.