Unfortunately, there is no way to directly check your registered password.
If you forgot your password, follow the steps below to change it.
Note: Be sure to write your new password down so you don’t forget it.
1. Tap the Home tab > Settings > Account.
2. Tap Password.
3. Enter your new password twice, then tap Change password.
Note: If your device is locked with a password or pattern lock, you‘ll be asked to unlock it when you change your password.
Tap here to open the Account screen from your smartphone.
You can also watch this video to learn how to configure your settings.
If you can’t remember your password and don't have access to your old device when transferring your LINE account, see this Help article.