4 ideas
At his Echigoya shop in Edo's Suruga-chō, Mitsui Kurōemon broke with the custom of selling on credit at haggled prices. He sold for cash at fixed marked prices, cut cloth to whatever length a customer wanted, and assigned each clerk a single type of fabric. The shop drew huge daily custom and made him a model millionaire, showing that redesigning the terms of trade can outearn simply working harder within the old terms.
Saikaku gives wealth as a mock prescription with dosages measured in ryō. The ingredients are early rising, attention to the family trade, night work, thrift, and good health, to be ground together and taken daily. It comes with a list of forbidden foods: luxuries, pleasure quarters, poetry and tea hobbies, and similar indulgences. Fortune is framed as the compounding of small daily disciplines plus the strict avoidance of specific named drains.
The Kyoto miser Fujiya Ichibei is visited by young men who want to learn how to become rich. He lectures them at length on thrift. When they hear grinding in the kitchen and hope for refreshments, he tells them it is only paste being made for ledger covers. He ends by saying that if he had served them food, that would not have been the way to become a millionaire, so the lesson is delivered through the refusal itself.
A borrower takes a small sum from Mizuma Temple's Kannon and lends it out to fishermen. The debt doubles each year, and after thirteen years it has grown into an enormous amount to return. Saikaku does the arithmetic explicitly, so the reader sees how a trivial principal, kept circulating at a steady rate, becomes a fortune through time rather than size.