Board Thread:Help and Questions/@comment-180.214.232.17-20150716095810/@comment-26005122-20150716163625

There are 3 usual reasons why that may happen.

They might be playing a different version of Tsum Tsum. There's the international and Japanese versions. If one is playing one version and the other person is playing the other version, you guys won't show up in each other's game.

They could have never registered Tsum Tsum with LINE, meaning they never even started playing it or they're on a guest account. In that case, they will show up under the Invite Friends section.

They could be newly invited friends on your LINE account, which will take a few hours for them to show up in your list, either on the ranking friends list or the Invite Friends list, accordingly.

If it's anything beyond those three, you may want to contact either LINE or the Tsum Tsum developer using the in-game contact form.