Riichi Mahjong (麻雀)
Overview
Riichi Mahjong is the Japanese variant of Mahjong, played by 4 players with 136 tiles. The objective is to build a complete winning hand of 14 tiles by drawing and discarding. A game consists of a hanchan (half-game): an East round (東場, rounds 1–4) and a South round (南場, rounds 5–8), for a total of up to 8 hands. Each player starts with 25,000 points.
Tile Types
There are 34 unique tile types, each appearing 4 times, for a total of 136 tiles.
Suited Tiles (数牌) — 108 tiles
| Suit | Japanese | Range | Count |
|---|
| Man (Characters) | 萬子 (マンズ) | 1m–9m | 4 each = 36 |
| Pin (Dots) | 筒子 (ピンズ) | 1p–9p | 4 each = 36 |
| Sou (Bamboo) | 索子 (ソーズ) | 1s–9s | 4 each = 36 |
- Terminals (老頭牌): 1 and 9 of each suit
- Simples (中張牌): 2–8 of each suit
Honor Tiles (字牌) — 28 tiles
| Type | Tiles | Count |
|---|
| Wind tiles (風牌) | East (東), South (南), West (西), North (北) | 4 each = 16 |
| Dragon tiles (三元牌) | White (白/Haku), Green (發/Hatsu), Red (中/Chun) | 4 each = 12 |
Red Fives (赤ドラ)
When the akaDora option is enabled (default: on), certain fives are designated as red fives: one 5m, two 5p, and one 5s (4 red tiles total). Red fives function identically to normal fives but each counts as 1 bonus han (dora).
Game Flow
Deal (配牌)
- The 136 tiles are shuffled and arranged into a wall.
- 14 tiles are set aside as the dead wall (王牌). The first tile of the dead wall is revealed as the dora indicator (ドラ表示牌).
- Each player receives 13 tiles. The dealer (親, East seat) receives a 14th tile and begins the first turn.
Turn Cycle
- Draw: The current player draws one tile from the live wall (牌山).
- Decision: After drawing, the player may declare Tsumo (win), Riichi, or Kan (closed/added). Otherwise, the player must discard one tile.
- Call Check: After a discard, all other players are checked for calls in priority order:
- Ron (win off the discard) — any player
- Kan (quad using the discard) — any player
- Pon (triplet using the discard) — any player
- Chi (sequence using the discard) — next player in turn order only
- If no call is made, play passes to the next player (counter-clockwise by seat).
A player who makes a call (chi, pon, or daiminkan) must discard a tile afterward (except for kan, which involves a supplemental draw first).
Winning Hand (和了形)
A winning hand contains 14 tiles (including the winning tile) and must match one of these patterns:
Standard Form (4 melds + 1 pair)
- 4 melds (面子) + 1 pair (雀頭)
- A meld is either:
- Shuntsu (順子): 3 consecutive tiles of the same suit (e.g., 2m-3m-4m)
- Koutsu (刻子): 3 identical tiles (e.g., 7p-7p-7p)
- Kantsu (槓子, quad of 4 identical tiles) counts as a meld for hand composition.
Chiitoitsu (七対子) — 7 Pairs
- 7 distinct pairs (all pairs must be different tile types)
Kokushi Musou (国士無双) — 13 Orphans
- One of each of the 13 terminal and honor tiles (1m, 9m, 1p, 9p, 1s, 9s, E, S, W, N, Haku, Hatsu, Chun) plus one duplicate of any of them.
Yaku Requirement
A winning hand must include at least 1 yaku (scoring pattern). Dora alone does not count as a yaku. A hand with no yaku cannot win even if it forms a valid pattern.
Calls (鳴き)
When a tile is discarded, other players may call it to form or complete melds. Making a call (except Ron) opens your hand (副露), which prevents certain yaku and may reduce han values.
Call Types
| Call | Meaning | Who Can Call | Requirement |
|---|
| Chi (チー) | Sequence | Next player only | 2 tiles from hand that form a sequence with the discard |
| Pon (ポン) | Triplet | Any player | 2 identical tiles from hand matching the discard |
| Kan (カン) | Quad | Any player | See Kan Types below |
| Ron (ロン) | Win | Any player | The discard completes a winning hand with yaku |
Call Priority
When multiple players want to call the same discard:
Ron > Kan/Pon > Chi
If multiple players declare Ron simultaneously, all winners are paid (double/triple ron), unless 3 players declare Ron — which triggers the sanchaho (三家和) abortive draw.
Kuikae Restriction (食い替え禁止)
After making a chi or pon call, the player cannot discard a tile that would make the call equivalent to a swap (taking a tile and giving back a functionally identical one). The forbidden tiles are:
- After Pon: Cannot discard a tile of the same kind as the called tile.
- After Chi: Cannot discard the called tile's kind (genbutsu), and cannot discard the tile on the opposite end that would form an alternative sequence with two of the meld's tiles (suji).
Examples:
- Chi 3p with 4p-5p → meld 3-4-5 → cannot discard 3p (genbutsu) or 6p (suji: 4-5-6)
- Chi 1m with 2m-3m → meld 1-2-3 → cannot discard 1m (genbutsu) or 4m (suji: 2-3-4)
- Chi 5s with 4s-6s → meld 4-5-6 → cannot discard 5s (genbutsu only; no suji for middle calls)
- Pon 7p → cannot discard 7p
Forbidden tiles are shown dimmed and cannot be selected for discard.
Riichi (立直)
Declaration Conditions
A player may declare Riichi when all of the following are true:
- Menzen (門前): The hand is fully closed (no open chi/pon/daiminkan; ankan is allowed).
- Tenpai (聴牌): The hand is one tile away from winning.
- Points: The player has at least 1,000 points to pay the Riichi deposit.
- Tiles remaining: At least 4 tiles remain in the live wall.
Effects
- The player places a 1,000-point stick on the table as a deposit (供託).
- The Riichi declaration tile is placed sideways in the discard row.
- +1 han is added to the hand if the player wins.
- The player's hand is locked: only tsumogiri (drawing and immediately discarding the drawn tile) is allowed, unless the drawn tile completes the hand.
- If the player wins, ura dora (裏ドラ) indicators are revealed for additional bonus han.
Double Riichi (ダブルリーチ)
If a player declares Riichi on their very first discard (before any calls have been made by anyone), it is a Double Riichi worth 2 han instead of 1.
Open Riichi (オープンリーチ)
When the openRiichi option is enabled (default: off), a player may choose to declare Open Riichi instead of normal Riichi. The player reveals their entire hand face-up, exposing it to all opponents. In exchange, Open Riichi is worth +2 han (instead of the normal +1 han from Riichi). Double Riichi and Open Riichi may combine for +4 han total. Ippatsu and ura dora still apply as normal. Because the hand is fully visible, opponents can clearly see which tiles would complete it — the risk is strategic, not informational. If an opponent deals into (振り込み) an Open Riichi player's winning tile, the payment is escalated to yakuman (役満払い) regardless of the hand's actual han value.
Ippatsu (一発)
If a Riichi declarer wins within one full turn cycle after declaring (before their next draw), and no calls (chi, pon, kan) interrupt the cycle, Ippatsu (+1 han) is awarded.
Kan Types (槓)
A kan (quad) is a set of 4 identical tiles. There are three types:
Ankan (暗槓) — Closed Quad
- Formed from 4 identical tiles all in hand (no called tile).
- Can be declared during your turn after drawing.
- The hand remains closed (門前). Ankan does not break menzen status.
- The 4 tiles are placed face-down (two outer tiles hidden) to indicate a closed meld.
Daiminkan (大明槓) — Open Quad
- Formed when you hold 3 identical tiles and another player discards the 4th.
- Called like a pon, but with 4 tiles instead of 3.
- The hand becomes open (副露).
Kakan (加槓) — Added Quad
- Formed by adding the 4th tile to an existing open pon (明刻).
- Can only be declared during your turn after drawing the matching tile.
- Other players may declare chankan (搶槓, robbing the kan) to win by Ron on this tile.
Kan Effects
- After any kan, a new dora indicator is revealed from the dead wall.
- The kan-declaring player draws a supplemental tile (嶺上牌) from the dead wall.
- Winning on the supplemental draw is Rinshan Kaihou (嶺上開花, +1 han).
- A maximum of 4 kans may be declared across all players in a single hand (the dead wall has only 4 supplemental tiles). No further kans may be declared after the 4th.
Furiten (振聴)
Furiten is a restriction that prevents a player from winning by Ron. A player in furiten can still win by Tsumo.
Discard Furiten (捨て牌振聴)
If any of your winning tiles (tiles that would complete your hand) exists in your own discard pile, you are in permanent furiten. You cannot Ron for the rest of the hand.
Temporary Furiten (同巡振聴)
If another player discards a tile you could win on and you choose not to call Ron, you enter temporary furiten. This lasts until your next draw opportunity.
Riichi Furiten (リーチ後振聴)
After declaring Riichi, if any player discards a tile you could win on and you do not (or cannot) call Ron, you enter permanent furiten for the remainder of the hand. You can only win by Tsumo.
Yaku List (役一覧)
A winning hand must contain at least one yaku. The following 33 yaku are implemented, plus bonus han.
1 Han (1翻)
| Yaku | Name | Condition |
|---|
| Riichi | 立直 | Declared Riichi with a closed tenpai hand. Menzen only. |
| Ippatsu | 一発 | Win within one turn after Riichi, with no intervening calls. Menzen only. |
| Menzen Tsumo | 門前清自摸和 | Win by self-draw with a fully closed hand. Menzen only. |
| Pinfu | 平和 | All 4 melds are shuntsu (sequences), pair is not yakuhai, wait is ryanmen (two-sided). Menzen only. 0 fu from melds. |
| Tanyao | 断幺九 | All tiles are simples (2–8). No terminals or honors. Open allowed if kuitan (openTanyao) is enabled. |
| Iipeikou | 一盃口 | Two identical sequences (same suit, same numbers). Menzen only. |
| Bakaze | 場風牌 | Triplet/quad of the round wind tile (e.g., East triplet during East round). |
| Jikaze | 自風牌 | Triplet/quad of the player's own seat wind tile. |
| Yakuhai Haku | 役牌 白 | Triplet/quad of White dragon (白). |
| Yakuhai Hatsu | 役牌 發 | Triplet/quad of Green dragon (發). |
| Yakuhai Chun | 役牌 中 | Triplet/quad of Red dragon (中). |
| Rinshan Kaihou | 嶺上開花 | Win on the supplemental tile drawn after declaring a kan. |
| Haitei | 海底摸月 | Win by self-draw on the very last tile from the wall. |
| Houtei | 河底撈魚 | Win by Ron on the very last discard of the hand. |
| Chankan | 搶槓 | Win by Ron on a tile another player uses for kakan (added quad). |
2 Han (2翻) — Reduced to 1 han when open
| Yaku | Name | Condition |
|---|
| Sanshoku Doujun | 三色同順 | Same sequence (same numbers) in all three suits. 2 han closed, 1 han open. |
| Ittsu | 一気通貫 | 1-2-3, 4-5-6, 7-8-9 sequences of the same suit. 2 han closed, 1 han open. |
| Chanta | 混全帯幺九 | Every meld and the pair contains a terminal or honor tile. Must include at least one honor. 2 han closed, 1 han open. |
2 Han (2翻)
| Yaku | Name | Condition |
|---|
| Toitoi | 対々和 | All 4 melds are koutsu/kantsu (triplets/quads). No sequences. |
| San Ankou | 三暗刻 | 3 closed triplets (including ankan). |
| Sanshoku Doukou | 三色同刻 | Same-number triplet in all three suits. |
| Sankantsu | 三槓子 | 3 kans (any type: ankan, daiminkan, or kakan). |
| Honroutou | 混老頭 | All tiles are terminals or honors. No simples. Always paired with toitoi or chiitoitsu. |
| Shousangen | 小三元 | 2 dragon triplets + dragon pair. Effectively worth 4 han (2 from shousangen + 2 from yakuhai). |
| Chiitoitsu | 七対子 | 7 distinct pairs. Menzen only. Fixed 25 fu. |
3 Han (3翻) — Reduced to 2 han when open
| Yaku | Name | Condition |
|---|
| Junchan | 純全帯幺九 | Every meld and the pair contains a terminal tile. No honors. 3 han closed, 2 han open. Supersedes chanta. |
| Honitsu | 混一色 | All tiles from one suit plus honor tiles. 3 han closed, 2 han open. |
3 Han (3翻)
| Yaku | Name | Condition |
|---|
| Ryanpeikou | 二盃口 | Two sets of identical sequences (effectively 4 sequences forming 2 pairs of duplicates). Menzen only. Supersedes iipeikou. |
6 Han (6翻) — Reduced to 5 han when open
| Yaku | Name | Condition |
|---|
| Chinitsu | 清一色 | All tiles from a single suit. No honors. 6 han closed, 5 han open. Supersedes honitsu. |
Yakuman (役満) — 13 han
| Yaku | Name | Condition |
|---|
| Kokushi Musou | 国士無双 | 13 different terminal/honor tiles + 1 duplicate. Menzen only. |
| Suu Ankou | 四暗刻 | 4 closed triplets. Menzen only. Ron on shanpon (double-pair wait) does not qualify. |
| Daisangen | 大三元 | Triplets/quads of all 3 dragons (白, 發, 中). |
| Shousuushii | 小四喜 | 3 wind triplets + wind pair. |
| Tsuuiisou | 字一色 | All tiles are honor tiles (winds and dragons only). |
| Chinroutou | 清老頭 | All tiles are terminals (1 and 9 only, no honors). |
| Ryuuiisou | 緑一色 | All tiles are green: 2s, 3s, 4s, 6s, 8s, and Hatsu (發). |
| Chuuren Poutou | 九蓮宝燈 | 1112345678999 of one suit + any extra tile of that suit. Menzen only. |
| Suu Kantsu | 四槓子 | 4 kans (any type). |
| Tenhou | 天和 | Dealer wins on the initial 14-tile deal (before any draws). Menzen only. |
| Chiihou | 地和 | Non-dealer wins on their first draw (before any calls have been made). Menzen only. |
Double Yakuman (ダブル役満) — 26 han
When the doubleYakuman option is enabled:
| Yaku | Name | Condition |
|---|
| Kokushi 13-Wait | 国士無双十三面待ち | Kokushi with a 13-sided wait (all 13 different terminals/honors in hand, waiting on any of them). |
| Suu Ankou Tanki | 四暗刻単騎 | Suu Ankou with a tanki (pair) wait. |
| Daisuushii | 大四喜 | Triplets/quads of all 4 winds. |
| Junsei Chuuren | 純正九蓮宝燈 | Pure Nine Gates: exactly 1112345678999 waiting for any tile of that suit (9-sided wait). |
Bonus Han (飜数ボーナス)
These add han but are not yaku — they cannot satisfy the 1-yaku minimum by themselves.
| Bonus | Name | Condition |
|---|
| Dora | ドラ | Each tile matching a dora indicator adds 1 han. The dora indicator shows the tile before the actual dora (e.g., indicator 3m → dora is 4m; indicator 9m → dora is 1m; indicator North → dora is East; indicator Chun → dora is Haku). |
| Ura Dora | 裏ドラ | Revealed only when a Riichi declarer wins. Ura dora indicators are underneath the regular dora indicators. Same counting rules as regular dora. |
| Aka Dora | 赤ドラ | Red fives (one 0m, two 0p, one 0s — 4 tiles total). Each red five in the winning hand adds 1 han. |
Scoring (点数計算)
Fu Calculation (符計算)
Fu (minipoints) represent the base difficulty of the hand's composition.
Base Fu
| Condition | Fu |
|---|
| Standard hand | 20 (副底) |
| Menzen Ron | +10 |
| Tsumo (non-pinfu) | +2 |
| Pinfu Tsumo | Fixed 20 (no additions) |
| Pinfu Ron | Fixed 30 |
| Chiitoitsu | Fixed 25 |
Meld Fu
| Meld Type | Simples (2–8) | Terminals/Honors (1,9,字) |
|---|
| Open shuntsu (sequence) | 0 | 0 |
| Closed shuntsu (sequence) | 0 | 0 |
| Open koutsu (triplet) | 2 | 4 |
| Closed koutsu (triplet) | 4 | 8 |
| Open kantsu (daiminkan/kakan) | 8 | 16 |
| Closed kantsu (ankan) | 16 | 32 |
Pair Fu (雀頭)
| Pair Type | Fu |
|---|
| Simples or non-yakuhai wind | 0 |
| Dragon tile | 2 |
| Round wind or seat wind | 2 |
| Double wind (round wind = seat wind) | 4 |
Wait Fu (待ち)
| Wait Type | Description | Fu |
|---|
| Ryanmen (両面) | Two-sided wait (e.g., waiting on 3 or 6 with 4-5) | 0 |
| Shanpon (双碰) | Two-pair wait (waiting to complete one of two triplets) | 0 |
| Kanchan (嵌張) | Closed wait (e.g., waiting on 5 with 4-6) | 2 |
| Penchan (辺張) | Edge wait (e.g., waiting on 3 with 1-2, or 7 with 8-9) | 2 |
| Tanki (単騎) | Pair wait (waiting for the pair tile) | 2 |
Rounding
Total fu is rounded up to the nearest 10. Exception: chiitoitsu is always exactly 25 fu.
If an open hand calculates to exactly 20 fu, it is rounded up to 30 fu (open pinfu / kuipin rule).
Base Points Formula
Base Points = fu × 2^(2 + han)
If base points reach or exceed 2000, the hand is capped at mangan level.
Score Levels
| Level | Han | Base Points |
|---|
| Normal | 1–4 | fu × 2^(2+han), max 1920 |
| Mangan (満貫) | 5 | 2,000 |
| Haneman (跳満) | 6–7 | 3,000 |
| Baiman (倍満) | 8–10 | 4,000 |
| Sanbaiman (三倍満) | 11–12 | 6,000 |
| Yakuman (役満) | 13+ | 8,000 (× number of yakuman) |
Round-up Mangan (切り上げ満貫): When the roundUpMangan option is enabled, 4 han / 30 fu and 3 han / 60 fu hands are rounded up to mangan.
Payment Table
All payments are rounded up to the nearest 100.
Ron (Direct hit — loser pays everything)
| Non-dealer wins | Dealer wins |
|---|
| Base formula | base × 4 | base × 6 |
| Mangan | 8,000 | 12,000 |
| Haneman | 12,000 | 18,000 |
| Baiman | 16,000 | 24,000 |
| Sanbaiman | 24,000 | 36,000 |
| Yakuman | 32,000 | 48,000 |
Tsumo (Self-draw — all opponents pay)
When a non-dealer wins:
| Dealer pays | Each non-dealer pays |
|---|
| Base formula | base × 2 | base × 1 |
| Mangan | 4,000 | 2,000 |
| Haneman | 6,000 | 3,000 |
| Baiman | 8,000 | 4,000 |
| Sanbaiman | 12,000 | 6,000 |
| Yakuman | 16,000 | 8,000 |
When a dealer wins (all opponents pay equally):
| Each player pays |
|---|
| Base formula | base × 2 |
| Mangan | 4,000 |
| Haneman | 6,000 |
| Baiman | 8,000 |
| Sanbaiman | 12,000 |
| Yakuman | 16,000 |
Honba Bonus (本場)
Each honba adds +300 points total to a Ron payment, or +100 per player to Tsumo payments.
Abortive Draws (途中流局)
The following situations cause the current hand to end in a draw:
Kyuushu Kyuuhai (九種九牌) — 9 Different Terminals/Honors
A player who has drawn 9 or more different terminal/honor tile types in their starting hand may declare an abortive draw on their first turn (before any calls have been made).
Suufonrenda (四風連打) — 4 Same Wind Discards
If all 4 players discard the same wind tile as their first discard, the hand is drawn.
Suukaisan (四槓散了) — 4 Kans by Multiple Players
If a total of 4 kans have been declared and they belong to 2 or more different players, the hand is drawn. (If one player holds all 4 kans, play continues for suukantsu.)
Sanchaho (三家和) — Triple Ron
If 3 players simultaneously declare Ron on the same discard, the hand is drawn.
Suuchariichi (四家立直) — 4 Riichi
If all 4 players have declared Riichi, the hand is drawn after the 4th Riichi discard (if no one wins on it).
Exhaustive Draw (荒牌流局)
When the live wall is depleted (no tiles remain to draw), the hand ends. Players who are tenpai receive points from those who are not tenpai (noten). Tenpai is determined by formal tenpai (keishiki tenpai) — a hand counts as tenpai if its shape is waiting, even if the player is in furiten or all waiting tiles have been discarded:
| Tenpai count | Tenpai receive | Noten pay |
|---|
| 1 tenpai | 3,000 | 1,000 each |
| 2 tenpai | 1,500 each | 1,500 each |
| 3 tenpai | 1,000 each | 3,000 |
| 0 or 4 tenpai | No payment | No payment |
Round Progression
Renchan (連荘) — Dealer Continuation
The dealer continues (the round number does not advance) if:
- The dealer wins the hand, OR
- The hand ends in a draw and the dealer is tenpai.
When the dealer continues, the honba counter increases by 1.
If the dealer does not win and is not tenpai at a draw, the deal passes to the next player and the round number advances. The honba counter resets to 0.
Hanchan End Conditions
The game ends when:
- All 8 rounds have been completed (South 4 is finished with no renchan), OR
- Any player's score drops below 0 points.
If the game ends during the South round and the dealer is in renchan, extra rounds may continue until the dealer fails to continue or another end condition is met.
Final Scoring (最終精算)
At the end of the hanchan, final scores are calculated:
1. Unclaimed Riichi Sticks
Any riichi sticks remaining on the table are awarded to the 1st-place player.
2. Oka (オカ)
Each player started with 25,000 but the base for calculation is 30,000. The difference (5,000 × 4 = 20,000) goes to the 1st-place player as the oka bonus.
3. Uma (ウマ)
Placement bonuses/penalties are applied:
| Placement | Uma |
|---|
| 1st | +15,000 |
| 2nd | +5,000 |
| 3rd | -5,000 |
| 4th | -15,000 |
4. Conversion
Final score for each player:
(raw score − 30,000 + uma + oka) ÷ 1,000 → rounded to nearest integer
The resulting values always sum to zero across all 4 players.
Variant Options
| Option | Default | Description |
|---|
| akaDora | On | Red fives (one 5m, two 5p, one 5s) count as bonus dora (+1 han each). |
| openTanyao (kuitan) | On | Tanyao (all simples) is allowed with an open hand. When off, tanyao requires menzen. |
| nagashiMangan | On | If a player's entire discard row consists of only terminals and honors at an exhaustive draw (and none were called), it counts as a mangan win. |
| doubleYakuman | On | Enables double-value yakuman for specific patterns: kokushi 13-wait, suu ankou tanki, daisuushii, junsei chuuren (26 han instead of 13). |
| roundUpMangan | Off | 4 han / 30 fu and 3 han / 60 fu hands are rounded up to mangan (instead of 7,700/7,900). |
| openRiichi | Off | Allows declaring Open Riichi (hand revealed) for +2 han instead of +1. Combinable with Double Riichi. |
