I recently got hooked on Disney Tsum Tsum. Logging in via the LINE messaging app lets you sync your game progress across devices and also gives you some free in-game coins so I thought I would try it.
I was able to get the app installed, but I have no idea how to log in to LINE from inside the Tsum Tsum game. It asks for an email address and password, neither of which I gave when creating my LINE account. It auto-sensed my mobile number and texted me a confirmation code and that was that; I never had to enter an email address nor pick a password.