I just got acquainted with the team members of the projects, they are from Japan, but the stock exchange was registered in Malta. Malta's legislation is friendly to cryptocurrency-based projects, so I think this is the most appropriate choice for the project.
What's the difference where the exchange is registered? Most exchanges are registered worldwide and few people care about it. The main thing is that its not real bots that trade there, but real people. The volume of trading may not be as large as other exchanges tell us about it, but it will be real.
The place of registration is important in the sense that in some jurisdictions there may be problems with financial regulators and government agencies because of which the exchange may be closed. In Malta, the government is loyal to crypto currency, so this is a favorable place to start the exchange.