Riichi Mahjong Rules (Japanese)

What is riichi mahjong?

Riichi is the Japanese form of mahjong and the most played version online. Structurally it is close to Hong Kong mahjong: 136 tiles, 13 in hand, chow allowed, four sets plus a pair.

Four additions make it a different game: the riichi declaration, the furiten penalty, dora tiles, and the requirement that every hand contain at least one yaku. The first three are tactical; the fourth decides which hands are legal.

The yaku requirement

A structurally complete hand with no yaku cannot be declared. This is the rule that surprises players coming from Chinese styles, where a complete shape is usually enough on its own.

In practice it means you must commit to a recognisable pattern. All simples, a dragon triplet, a seat wind triplet, a pure straight, a three-suit straight — pick one and build around it. If your hand ends up with no pattern, it is not a slow hand — it is an invalid one.

The twelve patterns worth learning first are on the riichi yaku list.

Riichi: the declaration

When your hand is one tile from completion and you have not claimed any tile, you may declare riichi. You place a 1000-point stick on the table, announce it, and from that moment you may not change your wait.

You gain a yaku immediately, access to uradora, and the pressure a visible declaration puts on everyone else. You also lose your cover: everyone knows you are close, and your discards become predictable.

Two restrictions matter. You cannot declare riichi after claiming a tile, and you cannot riichi with fewer than 1000 points. Once declared, only a concealed kong is allowed, and it must not change your wait.

Furiten

Furiten is the state of being unable to win on a discard, even though your hand is ready. It happens in three ways:

1. You discarded a tile you are now waiting on. The most common case by far.
2. You passed on a winning tile that another player discarded, and did not claim it.
3. Another player declared riichi and you passed their winning tile — temporary furiten, cleared at the next draw.

Furiten blocks only the win on a discard. A furiten hand can still win — you just have to draw the winning tile yourself.

Dora and uradora

At the start of the hand, one tile is revealed from the dead wall as the dora indicator. The tile immediately after it in sequence is the dora, and each copy in your hand adds one fan. Most tables flip a single indicator; a double-dora variant flips two. A kong reveals an extra indicator.

After a riichi win, the tiles beneath the indicators are revealed as uradora. Only the riichi player scores them. This is why riichi hands often jump from 3 fan to 8 fan without warning.

Dora is not a yaku. A hand with five dora and no pattern is still invalid.

Scoring: fu and fan

Japanese scoring combines a base value from fu (the shape of the hand) with a multiplier from fan. The base points are fu × 2^(fan+2), capped at fixed limits:

Name	Fan	Base points
Mangan	3–4 (with high fu) or 4–5	2000
Haneman	6–7	3000
Baiman	8–10	4000
Sanbaiman	11–12	6000
Yakuman	13+ or a listed hand	8000

The exact thresholds depend on whether the hand is closed and on the specific rule set. For practical play, learn the five names in order; the client or the scorer handles the arithmetic.

Claiming and the dead wall

Chow comes only from the left. Pung and kong come from any seat. Priority is win, then kong, then pung, then chow. The dead wall holds 14 tiles: it supplies kong replacements and the dora indicators, and is never drawn from directly.

Because kong replacements come from the dead wall, a kong does not shorten the live wall the way it does in Chinese styles. It does, however, reveal an extra dora indicator, which can help your opponents as much as you.

What to learn first

Three habits get a beginner through the first twenty hands:

• Pick a yaku immediately. All simples is the easiest: no terminals, no honours. Build toward it unless the deal says otherwise.
• Do not discard what you are waiting on. The single most common furiten mistake.
• Watch the dora indicator. A tile that looks ordinary may be worth a fan to the player holding it.

Defence in riichi is a skill of its own, covered on suji, kabe and safe tiles.

Quick answers

Can I declare riichi with an open hand?

No. Riichi requires a closed hand. If you have claimed a tile, you cannot declare it for the rest of that hand.

Does furiten stop me from winning entirely?

No. It blocks a win on another player's discard. You can still win by drawing the tile yourself.

Is dora a yaku?

No. Dora adds fan to a hand that already has a yaku. It cannot make an otherwise invalid hand legal.

What is uradora?

Dora revealed under the indicators after a riichi win. Only the player who declared riichi scores them.

Why can I not win with a complete hand?

Because it has no yaku. Riichi requires at least one recognised pattern in addition to the shape.