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hand structure riichi

Suukantsu

四槓子
(すうかんつ)

By Kenji Tanaka · Updated

Definition

Four kans by a single player, a yakuman and one of the least frequently completed hands in mahjong. Under many rules, four kans split across two or more players end the hand in an abortive draw instead, so only a solo collector can finish it.

Suukantsu

Suukantsu (四槓子, すうかんつ) is one of the rarest yakuman hands, requiring four kans (quads of four identical tiles) plus one pair. You need four sets of four identical tiles, 16 specific tiles from a 136-tile set, making it statistically one of the most difficult yakuman to achieve. Worth full yakuman points (32,000 total for a non-dealer, 48,000 for the dealer).

Understanding Suukantsu

Requirements

To achieve suukantsu, you must have:

  • Four kans: Any combination of ankan (concealed), minkan (open), or shouminkan (added kan)
  • One pair: The remaining two tiles form your pair

For example: 2-2-2-2 bamboo, 5-5-5-5 characters, 9-9-9-9 dots, East-East-East-East (four kans), plus a pair of 6-man.

Extreme Rarity

Suukantsu is legendarily rare:

  • Tile requirements: Sixteen specific tiles (four each of four types) from a set where only four of each tile exist
  • Draw probability: The statistical chance of collecting four complete sets of four tiles is infinitesimally small
  • Opponent interference: If opponents call pon or kan on tiles you need, suukantsu becomes impossible

Most players never achieve suukantsu even after decades of play. Each occurrence is typically photographed and celebrated.

Fifth Kan Rule (Suukaikan)

In most rule sets, if four kans are declared by two or more different players, the hand ends in an abortive draw called suukaikan (four kans by a single player do not trigger the draw). This rule prevents infinite kan chains.

Implication: If another player has already declared one or more kans, and you’re building suukantsu, be aware that the hand aborts as soon as the fourth total kan is declared across multiple players, making your suukantsu impossible once an opponent has kanned.

Kandora Bonanza

Each kan reveals one new kandora indicator. Four kans mean four extra kandora indicators beyond the initial dora. While suukantsu alone scores yakuman, the additional kandora are irrelevant for scoring (yakuman is already maximum). However, they help other players, which is a strategic consideration when declaring kans.

Strategic Considerations

Mixing Kan Types: You can combine ankan, minkan, and shouminkan freely. Most suukantsu hands involve at least some minkan calls since self-drawing 16 specific tiles is virtually impossible.

Toitoi Structure: Suukantsu is technically a form of toitoi (all triplets/quads) since kans are four-tile extensions of triplets. However, yakuman overrides toitoi, so you score only yakuman.

Opponent Awareness: Once you’ve declared three kans, opponents realize suukantsu potential and may adjust their discards to avoid completing your hand.

Suukantsu at the table

In an extraordinarily lucky hand, you draw four 4-bamboo tiles and declare ankan. An opponent discards 7-characters when you hold three, so you call kan (minkan). Later, you self-draw four White dragons and declare ankan again. Finally, you draw four South winds over several turns and declare ankan. Your hand: 4-4-4-4 bamboo, 7-7-7-7 characters, White-White-White-White, South-South-South-South (four kans), plus any pair. You win and declare suukantsu (yakuman), scoring 32,000 points as a non-dealer or 48,000 points as the dealer. Opponents marvel at the rarity, and you photograph the hand for posterity.