If your child is using Android smartphone/tablet, 4G LTE mobile phones, or miraie f, you can individually unblock (allow usage of) apps from the "Administrator Page" [管理者ページ].
Please follow the steps below from the parent's smartphone or computer.
From the parent's smartphone or computer, access the "Anshin Filter for au"[あんしんフィルター for au] administrator page [管理者ページ].
Enter the administrator ID (email address) and password, check the box "I am not a robot" [私はロボットではありません] then tap on "Login"[ログイン].
The administrator page will be displayed.
Tap on "App-specific settings"[アプリ別設定].
Scroll down the page and search for LINE app.
Tap on "Restrict"[規制]on the right side of LINE app.
Tap on "Allow individually" [個別に許可] .
Scroll to the top of the page and check if LINE is displayed as "Allowed"[許可] under "Set apps individually" [個別に設定したアプリ].
Tap on "Save settings" [設定を保存する].
This completes the setting to allow the use of LINE.
Has your problem been solved?