Ari-ari

Ari-ari

Ari-ari (ありあり) is the most widely used rule set in modern riichi mahjong, characterized by permitting both kuitan (open tanyao) and atozuke (winning with an incomplete yaku). The term literally means “there is, there is,” referring to the presence of these two allowances.

Detailed Explanation

In riichi mahjong, players must form winning hands (agari) that contain at least one yaku (scoring pattern). However, different rule sets impose varying restrictions on which yaku are valid and under what conditions hands can be won.

Kuitan Allowance

Kuitan (喰い断) refers to forming tanyao (all simples) through an open meld rather than a concealed hand. In ari-ari rules, this is permitted. This means a player can win with tanyao even if one or more melds are open (called, from the discard). Under stricter rule sets (nashi-nashi), kuitan is forbidden, requiring tanyao to be formed entirely from concealed tiles.

The allowance of kuitan significantly impacts hand selection strategy, as players can pursue tanyao more flexibly by calling tiles from opponents’ discards rather than waiting for a fully concealed hand.

Atozuke Allowance

Atozuke (後付け, literally “attach afterward”) refers to completing a yaku only upon winning. In ari-ari rules, this is allowed. For example, a player might call tiles to form a hand that lacks a yaku at the moment of calling, but gains a yaku when the final winning tile is drawn or claimed. Common scenarios include:

• Drawing a tile that completes a yaku simultaneously with completing the hand structure
• Winning with pinfu (no points) that becomes valid only upon drawing the winning tile
• Completing a yaku through the winning tile itself (such as forming a pair that completes a color sequence requirement)

In nashi-nashi rules, atozuke is forbidden; every yaku must be established before the winning tile is drawn.

Strategic Impact

The ari-ari rule set opens significantly more winning possibilities compared to nashi-nashi rules. Players have greater flexibility in hand development, can pursue open melds more aggressively, and have more opportunities to win with minimal yaku. This makes ari-ari more accessible to casual players while maintaining strategic depth.

The rule set encourages faster gameplay and more frequent winning hands, making it popular in casual clubs, online platforms, and tournament play worldwide.

Usage Example

Consider a player with a hand containing 2-3-4 of bamboo (open meld), 5-6-7 of bamboo (open meld), and 1-1 of characters (pair). They are waiting for 8-bamboo to complete the hand. Upon drawing 8-bamboo, they win with tanyao. This is valid under ari-ari rules because:

1. Kuitan is allowed, so tanyao formed with open melds is valid
2. Atozuke is allowed, so the yaku is established upon winning

Under nashi-nashi rules, this winning hand would be invalid.

Related Terms

Kuitan — Open tanyao; forming all simples through open melds. Allowed in ari-ari, forbidden in nashi-nashi.

Atozuke — Completing a yaku upon winning. Allowed in ari-ari, forbidden in nashi-nashi.

Nashi-nashi — The opposite rule set, where both kuitan and atozuke are forbidden, creating stricter winning requirements.

Agari — A winning hand; the completed hand formation that scores points.

Meld — An open combination of tiles (pung, kong, or chow) formed by calling from another player’s discard.

Yaku — A scoring pattern or hand pattern required to win in riichi mahjong.

Ari-ari remains the standard rule set for most modern riichi mahjong play, serving as the baseline for casual and competitive play alike.