らくでん -楽天でんわ用アプリ- is an Android application developed by Keisuke Kiuchi. This app is specifically designed for users of the Rakuten Denwa service. It allows users to easily make calls using the Rakuten Denwa service directly from their usual phone app, without the need for a separate phone book app.

With らくでん -楽天でんわ用アプリ-, users can enjoy the following features:

• Automatically adds the prefix "" when making outgoing calls using Rakuten Denwa.
• Allows users to register phone numbers that should not be subject to the prefix conversion.
• Provides the option to set the default phone app to launch from the settings.
• Allows users to change the prefix number.
• Automatically ignores freephone numbers0570) if desired.
• Automatically ignores numbers starting with 5 digits, *, or # (e.g. 110, 117) to prevent adding the prefix when calling emergency or special service numbers.
• Takes into account Rakuten Denwa-compatible international numbers and adds the appropriate prefix.

Please note that this app has ceased development, and no updates will be provided except for critical bug fixes.