Tochuu ryuukoku (途中流局) is more commonly known as an abortive draw. Specific game situations end a kyoku (hand session) without any player declaring a win or drawing all tiles from the wall. With the exception of kyuushuu kyuuhai, all cases of tochuu ryuukoku are mandatory.
The current hand is instantly aborted. The noten penalty is not imposed and riichi declarers do not have to reveal their hand.
Riichi bets remain on the table and can be won during the next hand. As with an exhaustive draw, the honba count increases by one.
The seat winds do not rotate for the next hand, which is considered a repeat of the aborted hand.
The following screnarios cause an abortive draw.
The first discard of each player is the same wind tile.
A player's 14-tile hand after his initial draw is composed of 9 different honor or terminal tiles. The player may announce this and reveal his hand, then the hand is aborted. This option is only available if no tile call has interrupted the set of turns earlier. Instead of calling kyuushuu kyuuhai, a player may play the hand normally, maybe aiming for kokushi musou. This is the only case where the call for tochuu ryuukoku is optional.
All four players call riichi and the 4th player's discard is not a winning tile.
Kan is called four times by different players. If all four quads are called by one player, play continues as to give the player the opportunity to score the yakuman, suu kantsu. No other players are allowed to declare kan from then on. If the four quads have been formed by more than one player, hand abortion after formation of the fourth quad depends on the rules.
- Most rules abort the hand when the following discard is not a winning tile.
- Some rules end the game already on declaration of the fourth quad.
- Some rules may allow the game to go on, as if all quads had been declared by a single player. Usually, a fith kan may not be declared at all, but when it is allowed, it immedeately aborts the game on its declaration.
In some rules, if three players call ron on the same tile, the hand is aborted and no player wins.