What are the processes if I want to start a small company in Japan?ja

Well, simply put, first you have to find property that you can rent. Then you might want to consider going to  the health care centre for consult about needed licenses depending on your kind of business. Or you can go ahead an make an application for a business license and find a food hygiene manager and then present these to a health care centre.
When you have your rental contract and all the needed licenses you can purchase all those things needed for your restaurant and open!