This isn't as far-fetched as it sounds. Japan is one the largest cryptocurrency markets, and it still has a huge user base even when you don't include its other products. Its existing payment service has about 40 million users, and this would be a logical extension. New financial services could give Line a healthy source of revenue and lock people in, whether they want to insure their apartment or buy a new car.

As it stands, Line isn't betting solely on finance. It just struck a deal that gives wireless giant SoftBank a controlling 51 percent stake of its Line Mobile cellular service. It's far from giant with a value of about $15 million, but this gives Line a boost while letting SoftBank wrap its fingers around yet another cell network. Don't be surprised if Line Mobile grows beyond its fledgling roots, even if it's unlikely to have a global presence.