A year ago, LINE has released their port of LINE Messenger for Windows Phones though the app lacked a lot of features as compared to their Android and iOS counterparts. The WP port lacks the free calls function which is an important feature.

It is heavily advertised in their TV and web advertisements. It even includes the Windows Phone logo on the last part of the TV ad. This gives a disappointment to WP users and the app has a bad reputation at the Windows Phone Store (you may check it out). I also checked their website and they don't have a support section where you can raise concerns for privacy, technical issues and the like.
They can be contacted through their Facebook fanpages and Twitter accounts though they don't reply.

The port also has a limited set of stickers that can be downloaded as compared to Android and iOS. The same goes to themes, games and other apps that they offer.

Your signature means a lot for the Windows Phone users who use LINE Messenger. If you are a Windows Phone user, or your friend or a family member uses one, please sign this! Thank you!