Special Draws and Edge Rules

25.1 Exhaustive Draw (流局, Ryuukyoku)

When the live wall is depleted without anyone winning, an exhaustive draw occurs. Players who are tenpai receive noten payments from players who are not tenpai (see Module 12). Riichi deposits remain on the table. The dealer keeps their position if they are tenpai.

25.2 Abortive Draws (途中流局)

Certain special conditions can abort a hand before the wall is exhausted. These are called abortive draws (途中流局, tochuu ryuukyoku). Whether these rules apply depends on the ruleset. Common abortive draws include:

Kyuushu Kyuuhai (九種九牌) — Nine Different Terminals/Honors

If a player has 9 or more different yaochuuhai (terminals + honors) in their starting hand (before any calls have been made), they may declare an abortive draw. This is optional—the player may choose to continue playing (perhaps pursuing kokushi musou). The declaration must be made before any player has called tiles.

Suufon Renda (四風連打) — Four-Wind Discard

If all four players discard the same wind tile on their first turn (before any calls), the hand is aborted. This is an extremely rare event.

Suucha Riichi (四家立直) — Four Riichi

If all four players declare riichi, the hand is aborted after the fourth riichi declaration (unless the fourth riichi results in an immediate win). This is also very rare.

Suukaikan (四開槓) — Four Kans

If four kans are declared across all players (not all by the same player), the hand is aborted. If all four kans are declared by the same player, the hand continues (they may be pursuing suu kantsu yakuman).

Sanchahou (三家和) — Triple Ron

If three players simultaneously declare ron on the same discard, the hand is aborted in rulesets that use this rule. In rulesets with double/triple ron, all three players win instead.

25.3 Nagashi Mangan (流し満貫)

If, at the point of exhaustive draw, ALL of a players discards consist of only terminal and honor tiles, AND none of their discards were called by other players, they receive mangan payment. This is treated as a tsumo win for payment purposes. Nagashi mangan is very rare in practice because it requires an entire hands worth of discards to be exclusively yaochuuhai with none called away.

25.4 Abortive Draws in Practice — Frequency and Strategy

Abortive draws are rare in practice. Data from Tenhou shows approximate frequencies: Kyuushu kyuuhai (nine terminals) is declared in roughly 1-2% of hands. Suufon renda (four winds) occurs in roughly 0.01% of hands. Suucha riichi (four riichi) occurs in roughly 0.001% of hands. Nagashi mangan is achieved in roughly 0.05-0.1% of hands.

The most strategically interesting is kyuushu kyuuhai, where you must decide: declare the abortive draw, or continue and pursue kokushi musou? The decision depends on your specific tile count. If you have 9-10 different yaochuuhai, you are 3-4 tiles away from kokushi — achievable but unlikely. If you have 11-12 different yaochuuhai, kokushi becomes much more viable. Japanese professional player Seto Kumiko (瀬戸熊直樹) has discussed this decision point in tournament commentary, noting that the excitement of pursuing kokushi often leads amateurs to continue when declaring the draw would be objectively better for their placement.