East Round
By Kenji Tanaka · Updated
Definition
The East round (tonba) opens every game, with East as the prevailing wind: East triplets score yakuhai for everyone, and the deal passes once through all four seats. A tonpuu game ends when it does; a hanchan continues into the South round. It is where positions get established and where hot dealers do their early damage.
East Round
East Round (東場, とんば) is the first round of a standard hanchan (full game) in riichi mahjong, where the prevailing round wind is East. Each of the four players takes at least one turn as dealer during this round, resulting in a minimum of four hands played.
How East Round works
Structure
A hanchan consists of two rounds:
- East Round (Tonba): Round wind is East
- South Round (Nanba): Round wind is South
Each round guarantees that all four players serve as dealer at least once. Since the dealer rotates counterclockwise and can repeat dealership by winning or drawing in tenpai, an East Round typically lasts 4-8 hands depending on dealer wins.
Round Wind Significance
During East Round, the round wind is East. This affects scoring in two ways:
Yakuhai Value: Players holding triplets of East wind tiles earn yakuhai (1 han) because East matches the round wind, regardless of their seat wind. For the player seated as East, a triplet of East tiles provides 2 han (round wind + seat wind).
Dealer Advantage: The starting dealer (seated East) in the East Round has a scoring advantage, dealer wins pay 1.5× the normal amount. If the dealer wins repeatedly, they can accumulate significant point leads before other players get their dealer turns.
Round Progression
Dealer Rotation: After each hand, if the dealer doesn’t win (and isn’t in tenpai during a draw), dealership passes counterclockwise. The round continues until all four players have served as dealer at least once.
Transition to South Round: Once all four players have been dealer and the current dealer fails to win or draw in tenpai, the game transitions to South Round. The same rotation system continues with South as the prevailing wind.
Tonpuu Rule (East-only games): Some shorter game formats play only the East Round, ending after four hands (or when dealer rotations complete). These are called “tonpuu” games and last about half as long as full hanchans.
Seeing East Round in play
The game begins in East Round with Player 1 as the initial dealer (seat wind East, round wind East). Player 1 wins their first hand with a triplet of East tiles, scoring 2 han from yakuhai (seat wind + round wind). Because they won, Player 1 retains dealership for the next hand (renchan). After Player 1 finally loses a hand, dealership rotates to Player 2. The East Round continues until all players have been dealer at least once, then transitions to South Round.
Related Terms
South Round
南場
The South round (nanba) is the back half of a hanchan, with South triplets now scoring as the round wind. It contains the endgame: placement decides most rule sets, so the score gaps start dictating play, trailing players push, leaders defend, and the final hand (all-last) is the sharpest positioning moment in the game.
Tonpuu
東風
Tonpuu (tonpuusen) is the East-only game, half the length of a full hanchan: the deal passes once around the table and the game ends. It is the default for quick online matches. The compression changes strategy more than beginners expect. With no South round to repair a bad start, early leads harden fast, aggressive lines get rewarded, and the placement math of the endgame arrives by the fourth hand instead of the eighth.
Hanchan
半荘
A hanchan is the standard game length: an East round plus a South round, the deal passing through all four seats in each, for a minimum of eight hands. It is the format serious play assumes; tonpuusen, the East-only game, is the quick alternative. Early hands reward building value, and the late South round turns into a placement battle where the score gaps dictate who pushes and who protects.