Unless you really have to apply in Japan, I wouldn't recommend it. From seeing other people's experiences, it seems way easier and quicker to do it in south east asian countries
Sorry to hear this. I think you burnt yourself with the first freelance attempt, perhaps would have been different if you'd tried the Muay Thai route first time around. I don't think that being a landlord of a property and gaining income that way counts as freelance work (in their eyes). But don't dispair, try from another country with the Muay Thai attempt, Cambodia, Vietnam etc. You can do it!