There is a minimum capitilisation requirement of 5M JPY to sponsor a visa. For people starting a company and coming in on a business visa (forget the actual name), you will need at least 5M JPY in your company. This is to ensure that your company has enough money to support you for a year. This amount is very much dependent upon a variety of factors, so it may be more than 5M JPY, as far as I know.

The money is still held by your company and you can own the stock, so it's not like you are "spending" it.