Wow this is really an innovative strategy to promote bitcoin. Bitcoin has relatively gone so far on its mileage of achievement though there are many critics on it but still bitcoin continue to strive and prove its worth. Well i had enough loan on bank and i am not qualified on this even if they offer it outside on their country.
Exchanges in Japan looks like banks, they applied KYC and AML regulations, so using a loan in BTC seems very similar when you use a normal bank's loan. The difference is that if you don't have incomes in BTC, you can have a problem with the exchange rate (e.g. if the BTC price goes to the moon, you have to pay back much more in fiat compared to the amount you have received in the beginning)