From the LINE statement:
LINE Corporation, owner and operator of the free call and messaging app LINE, today announced its decision to discontinue the operations of its subsidiary MixRadio Limited. The MixRadio music streaming service will be discontinued in the coming weeks as we work with the technical team and partners to ensure a smooth closure.
•Reasons for Termination of MixRadio Operations
LINE agreed to acquire the business and assets making up the music service known as MixRadio from Microsoft Mobile OY in December 2014. The newly established company continued to provide a radio-style music streaming service intended to provide a broader user experience. Nevertheless, after a careful assessment of the subsidiary’s overall performance, the financial challenges posed by the music streaming market, and priorities of LINE Corporation, LINE has determined that future growth would be difficult to ensure and decided to discontinue the MixRadio music streaming service.
LINE and the MixRadio team would like to thank the users of MixRadio for all of their support of the service.
Well, that's that then. But a free, streaming music service only works if there's enough of a commercial back end for users to buy through. MixRadio never really had that chance and so its days were always numbered.
There are plenty of alternatives in the music streaming world, of course, even on Windows Phone and Windows 10 Mobile, but it's a shame to see a service with so much character and human investment die in such an ignominious way.