I think you are referring to the special startup visa that some cities in Japan are offering.Using this, it is possible to setup a company for as little as 1 yen but you will eventually be required to invest minimum 5 million yen and if you read into the OP's question a little deeper, you will understand that he is trying to setup a business to remain in Japan, i.e. for the purpose of a visa or visa extension but as I and others have explained, setting up a business and extending or changing a visa are two separate things.I think you will find that although there are special cases, to setup a company as a foreigner properly an appropriate "business manager" visa and other conditions are required.But, the OP should consult a legal expert anyway.