So I was talking to some of my Japanese penpals and they say that they have a easier time using LINE and Skype to learn english. I already have a LINE and I use it to chat with them,but do you think it's a good way to learn Japanese?
If you want to learn casual Japanese, I say "yes". In my experience, people hesitate to indicate mistake in my English. So, I think you should tell your friend you don't want your friend to hesitate to indicate mistakes in your Japanese.