Born into a low-ranking family, Nyûi developed a friendship with karô Tsugaru Mondo, and managed to rise through the ranks, from apprentice page (hôkô minarai) in 1735, to one of the most powerful positions in the domain less than 20 years later. He became head of the Hirosaki castle kitchen staff (zenban) in 1744, valet (konandoyaku) the following year, personal secretary (kinju koshô) in 1749, and financial magistrate (kanjô bugyô) in 1753.
Nyûi rejected Neo-Confucianism after the school of Zhu Xi as too abstract, drawing instead upon the teachings of Ogyû Sorai, Dazai Shundai, and Yamaga Sokô, as well as the Taoist teachings of Lao Tzu and Zhuangzi, in engaging with matters of statecraft and political economy. He emphasized the idea that all things have a given purpose or "utility" (yô, 用), and suggested that one of the chief economic roles of government was to ensure that necessities flowed without scarcity or abundance, without the price fluctuations caused by supply and demand; as an example, he often cited well water, which is drawn only when needed, and is always available if needed, thus creating no surplus, no excessive abundance, and no market in water.
Merchants did serve a purpose in Nyûi's philosophy, as transporting goods from areas of abundance to areas of scarcity served to help restore equilibrium and "order." Nyûi had a distaste, however, for price speculation, which he saw as injurious both to the "state" and to the merchants themselves, who would inevitably come to financial ruin if they ever predicted poorly. To this end, Nyûi had the domain impose a series of regulations for merchants in 1753, including sumptuary regulations, and a policy of exporting promissory notes instead of actual rice. This had some great effects, allowing the domain by 1755 to stop "borrowing" against retainer stipends. The increased stores of rice amassed as a result of not exporting it also helped the domain survive a considerable harvest shortfall that year. After this, Nyûi was granted the title of "general overseer" (motoshi) and gained an even more dominant position in the domain's administration.
Emboldened by his successes, Nyûi moved to more severely restrict merchant activity, and to have the domain take control more extensively of the economy, in order to better align commercial activity with his philosophical ideals. He issued bills known as hyôfu, ordering that these be used instead of hard currency in all exchanges, and mandating that merchants accept them as legal tender. Nyûi also obliged all merchants to forgive all samurai debt, and had the domain take on debt owed to merchants outside the domain. He also established a redistribution office, which redistributed merchant property to samurai. Merchants were restricted to working in only one type of goods each, and their activities and revenues were to be closely watched by the domain government.
As was often the case with domain currencies, the hyôfu were not widely accepted despite governmental mandates, and saw extreme inflation / depreciation almost immediately. By 1757, domain elites began to reverse Nyûi's policies, seeing them as too damaging; the following year, he was dismissed from his post and placed under house arrest. He was pardoned twenty years later, in 1778.
- Mark Ravina, Land and Lordship in Early Modern Japan, Stanford University Press (1999), 123-127.