# JANBU: Riichi Mahjong Trainer — Safe tiles, waits, efficiency

> Safe tiles, waits, efficiency (iPhone/iPad app by Atsushi Sashida.)

- Source: https://appshunter.io/ios/app/janbu-riichi-mahjong-trainer/id6811624599 (this page in markdown: same URL + `.md`)
- Developer: [Atsushi Sashida](https://appshunter.io/developer/6811624601)
- Category: Games, Board, Puzzle
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 16.0 · 84 MB
- Languages: American English, French (France), Japanese, Korean, European Portuguese, Russian, Chinese (Simplified, China), European Spanish, Chinese (Traditional, Taiwan)
- Released: 2026-09-20
- Data updated: 2026-10-18

## What is JANBU?

A practice-only app, fully playable in 9 languages.
It gives you the hardest moment of a hand, and checks whether your discard was really the best
one - with the numbers behind that answer.

English / Español / Português / Русский / Français / 한국어 / 繁體中文 / 简体中文 / 日本語
(the screenshots are in Japanese, but every screen is translated)


IT DOES NOT STOP AT RIGHT OR WRONG

After each answer, JANBU shows you exactly what it looked at to reach that risk figure.

- The deal-in rate for all 34 tiles, in colour and per cent
- Why each of your own 14 tiles is dangerous: ryanmen 10.3% / kanchan 2.5% / tanki 0.4%, broken down by wait shape and by opponent
- Expected loss = risk x estimated hand value, so you can decide whether to push or fold
- For discard problems, every legal discard listed side by side with its acceptance count
- For wait reading, the shape is taken apart: where the block is, which sets to peel off


FIVE MODES

Safe Tiles - pick five tiles that get through against a riichi
Full Defense - survive one discard per turn until the hand ends
Widest Wait - discard one of 14 tiles for the tenpai with the most winning tiles left
Wait Reading - name every waiting tile in 7-, 10- and 13-tile full-flush shapes
Time Attack - how many multi-sided waits can you solve before time runs out


IT DOES NOT RUN OUT

The wait shapes in Wait Reading and Time Attack were counted exhaustively: 46,425 of them.
7-tile 3,534, 7-tile+ 315, 10-tile 8,046, 13-tile full flush 34,530.

Safe Tiles and Full Defense deal a fresh wall every time: twenty thousand generated
positions produced zero repeats. Widest Wait draws from over 100,000 possible hands.


FOUR DIFFICULTY LEVELS

Beginner - find the safe tiles
Intermediate - read suji and walls
Advanced - tedashi/tsumogiri and two threats
Master - includes reading silent tenpai (damaten)


WHERE THE NUMBERS COME FROM

Each wait shape (ryanmen, kanchan, penchan, shanpon, tanki) is weighted by how likely it is,
multiplied by how many of the relevant tiles are still unseen, with furiten shapes removed.
Only public information is used. The app never looks at concealed hands or the wall.

Scoring follows the current official tournament rules.


A CALM PLACE TO CONCENTRATE

The paid version lets you pick a different track for each mode.


SAVE THE ONES YOU GOT WRONG

Any question can be added to Saved problems. The exact same board is rebuilt, so you can redo
it as many times as you like. You can attach a note and write, in your own words, why you got
it wrong. Up to 50 per mode, and you can lock the ones you never want dropped.

Any question can also be turned into an image. The answer is not included, so you can show it
to someone else as a puzzle.


THE PAID VERSION

All five modes are playable for free.
The paid version lets you go back to the reason you got it wrong.

- Review - reopen the question you just answered and see why your choice was not the best
- The risk map, and the per-tile explanation for each of your own 14 tiles
- Turn-by-turn review in Full Defense - trace which wait shapes died, and when
- Advanced and Master in Safe Tiles and Full Defense (tedashi and damaten reading)
- Similar problems - questions with the same shape as your saved ones, mixed in at random
- Background colours and BGM selection


ALSO

- No internet connection required. Everything runs on your device
- No ads
- Your results stay on your device and are never transmitted
- iPhone, landscape only
- 日本語 / English / Español / Português / Русский / Français / 한국어 / 繁體中文 / 简体中文

Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

## Pricing and in-app purchases

Base price: Free.

**Subscriptions**

| Subscription | Price | Period |
| --- | --- | --- |
| JANBU Pro (Yearly) | $49.99 | per year |
| JANBU Pro (Monthly) | $4.99 | per month |


## Is JANBU safe?

Not enough ratings yet to assess JANBU.

## Is JANBU legit?

JANBU: Riichi Mahjong Trainer has limited verification signals. The AppsHunter Legitimacy Score for JANBU is 58 out of 100 points across 7 verification signals from App Store and developer data.


## Version history (last 3 releases)

### 1.1.1 — 2026-10-05

Halloween edition. The title screen, mode select and app icon are dressed up for Halloween until the end of October. You can switch back to the standard look in MENU → "Title screen".

### 1.1.0 — 2026-09-26

SAVED PROBLEMS

You can now keep the questions you got wrong, or hesitated over, together with a note.
The exact same board is rebuilt later, so you can redo it as many times as you like.

- Available in all five modes
- Up to 50 per mode
- Lock the ones you never want dropped
- Replay a single saved problem, or all of them in random order

TURN A PROBLEM INTO AN IMAGE

Any position can be saved as an image. The answer is not included, so you can show it
to someone else as a puzzle.

SIMILAR PROBLEMS (PAID)

Questions with the same shape as your saved ones are mixed in at random positions,
so you can drill the shapes you are weakest at.

RULE CORRECTIONS

In rare cases a tile taken by a call was not treated as a safe discard. This has been
fixed, along with the side the called tile is laid on.
We also reviewed kan ura dora, haitei/houtei and the wall count, and added counted yakuman.

### 1.0 — 2026-09-21

No release notes.

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-10-18.*