雀舞 JANBU
A solo training app for mahjong defence
Support
Last updated: 2026-09-07
About JANBU
A solo training app for mahjong defence — knowing which tile is safe and which is dangerous. You do not play a game: the app presents positions after a riichi or a call and checks whether the tiles you chose were really the best ones. Danger is computed from public information only: your own hand, the four discard piles, the calls, and the dora indicator.
Requirements
- iPhone (iOS 16.0 or later)
- Designed for landscape orientation
- No internet connection required
- No advertising
Frequently asked questions
My results or best score disappeared
Results are stored only on your device. Deleting the app deletes them, and they cannot be restored.
There is no sound
Tap the title screen once to enable sound. If it is still silent, check the ring/silent switch on the side of your iPhone, the device volume, and the volume slider in MENU.
How do I change the language?
Use the selector at the bottom of the title screen, or MENU during play. Nine languages are available: Japanese, English, Spanish, Portuguese, Russian, French, Korean, Traditional Chinese and Simplified Chinese.
How is the danger percentage calculated?
The app weighs how likely each wait shape is (ryanmen, kanchan, penchan, shanpon, tanki), multiplies by how many of the relevant tiles are still unseen, and removes shapes excluded by furiten. It never looks at the concealed hands or the wall.
Does the app involve gambling?
No. The point values shown are a training yardstick. There is no exchange of money or virtual currency.
Reporting a problem
Including these four things makes a problem far quicker to track down: your iPhone model, your iOS version, which mode and difficulty you were in, and how to reproduce it.
Credits
Some sound effects and music come from Springin' Sound Stock. The remaining audio was produced for this app. The logo and background artwork are the developer's own work.