# JANBU: Riichi Mahjong Trainer > Safe tiles, waits, efficiency Canonical page: [https://chrome-stats.com/d/id6811624599](https://chrome-stats.com/d/id6811624599) ## Overview - **ID:** `id6811624599` - **Platform:** Apple - **Type:** Apple app - **Status:** Available - **Publisher:** Atsushi Sashida - **Category:** Board - **Version:** 1.0 - **Last updated:** 2026-09-21 - **First published:** 2026-09-20 - **Size:** 77 MB - **Data as of:** 2026-09-24 - **Store listing:** [Apple App Store](https://apps.apple.com/us/app/janbu-riichi-mahjong-trainer/id6811624599) - **Privacy policy:** [https://momonari-junta.github.io/janbu-site/privacy.html](https://momonari-junta.github.io/janbu-site/privacy.html) ## Description Fully playable in 9 languages. 46,425 wait shapes, counted exhaustively. Deal-in rates for all 34 tiles, why each of your 14 is dangerous, and the odds by wait shape. 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. 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) - 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/ ## Rankings - #2,146,817 — Overall ## Similar extensions and apps - [Mahjong Solo Issou](https://chrome-stats.com/d/id6755676628) — 5.00 / 5 - [Riichi Mah-jong Helper](https://chrome-stats.com/d/id1329138513) — 5.00 / 5 - [Mahjong Shanten Calculator](https://chrome-stats.com/d/id961845391) - [JantakuAR](https://chrome-stats.com/d/id6794878708) - [TileSlash: Riichi Mahjong](https://chrome-stats.com/d/id6778444002) - [Mahjong Quiz: What to Discard](https://chrome-stats.com/d/id6778321565) - [Sichuan Mahjong Trainer](https://chrome-stats.com/d/id6761172617) - [Riichi Mahjong Odds Calculator](https://chrome-stats.com/d/id6785065450) - [Riichi Sensei](https://chrome-stats.com/d/id6747702966) - [Riichi Mahjong Score Calc](https://chrome-stats.com/d/id6782329880) - [Mahjong Fold Dojo](https://chrome-stats.com/d/id6763664588) — 5.00 / 5 - [RiichiKun: Mahjong Calculator](https://chrome-stats.com/d/id6749703685) --- Source: [Chrome-Stats](https://chrome-stats.com/d/id6811624599)