This is one way of getting the name out of crypto to the public but there are some risks in this kind of business for btc value is very volatile. I know that people in Japan are very trustworthy so no problems with the paying time of the lenders. The only thing that is the problem is the value of bitcoin which is very unpredictable. If someone will loan 1btc for just $5k and suddenly after a month the BTC will increase its value 2 times then the one who loaned it will be paying double for a BTC loan. This is the risk when it comes to loaning BTC.