I'm visiting Japan quite often and made some Japanese friends.
Line is quite popular, partly because you can exchange IDs instead of phonenumbers and the stickers. You can see that Japanese people value privacy if you log in to their PC client => all data on your phone is wiped, which is a bit unconvienent for me.<p>I think it's funny how every other app now copies the line stickers. Facebook does it too, but I'm not sure if it's really catching on here. Japan really likes cute stuff and since the language is a lot more polite and indirect it's probably easier to communicate with stickers.<p>Line is much better than WeChat tough, which has bad layout, low quality emoticons and doesn't feel native.<p>WeChat's feature for finding users closeby who opt-in
is great. Please check that out, if you are an app developer!<p>I like Viber more, because their client works everywhere, actual voice calling is included, the software is fast and nice and they have great support, no battery drain like skype.