When you are considering to start a business, the most important consideration is whether the venture will result in value creation, which can be determined by estimating the of the venture. That is, you must compare the initial investment with the expected discounted cashflow over the life of the business. For example, if you are considering to open a cafe in Beppu, which would require an initial investment of 5,000,000 yen, you will need to earn an annual cashflow of at least yen (in units and no 1000 separators) if you believe that the appropriate discount rate is 20%, and assume that there is no opportunity for growth.