While the basic rules to mahjong apply with the Japanese variation, an additional, distinct set of rules are applied.
and Hand types, or , are specific combinations of tiles or conditions that yield the value of hands. Unlike many variants, a winning hand must have at least one . When scoring, each has its own value, with every approximately doubling the value of a hand up to a limit. A is a rare with stringent criteria which automatically scores the maximum number of points, ignoring any other scoring patterns. In some variations, multiple can be scored at the same time. ====== Declaring means declaring a ready hand, and is a kind of Japanese Mahjong yaku|. A player may declare a ready hand if their hand needs only one tile to complete a legal hand (), and the player has not claimed another players' discards to make
open melds. When declaring , the player must place their 1,000-point stick and place their discarded tile sideways; the hand is then fixed and may not be changed except when forming certain closed quads. After declaring a ready hand, a player can win on any drawn or discarded tile even if their hand has no other . As a possible house rule, a player can choose to reveal their hand when declaring to win more points if successful, which is called . In that case, the player shows only the tiles that are related to
waits, or reveals all the tiles in the hand depending on the rules. The declaration increases the count allowing the player to score extra points.
Dora are bonus tiles that add value to a winning hand. Every kind of tile can become a bonus tile, allowing its value to increment based on the amount of its corresponding "indicator" tiles. Bonus tiles are not counted as , regardless of the number of tiles present; the player still must form a in order to count. At the start of a hand, the upper tile from the third stack from the back end of the dead wall is flipped and becomes a bonus tile indicator. A tile of a next succeeding number or color is the bonus tile. For example, if an indicator is a Green dragon (), Red dragons () are counted as a bonus tile by the sequence shown below, in which the Red dragon wraps around to the White dragon (). The succeeding order of bonus tile is as follows: →→→→→→→→→ →→→→→→→→→ →→→→→→→→→ →→→→ →→→ The number of bonus tile indicators increases in the following manner: each time a player calls a
quad, the next adjacent bonus indicator tile is flipped, starting with the upper tile from the fourth stack from the back end. The indicator is flipped immediately after the quad is called, and after that the player draws a supplemental tile for their hand from the back end of the dead wall. The number of indicators increases in that direction, which becomes five if a single player calls four quads, and that is the largest possible number from the upper tiles in the third to seventh stacks of the dead wall (see
four quads). Additional bonus points can be awarded in the following situations: • : when a player wins with a
ready hand declaration, the tiles underneath the bonus tile indicators become additional bonus tile indicators as well. • : a variation uses specially marked red number 5 tiles that are also bonus tiles, regardless of whether it is indicated or not. The red 5 tiles also stack with normal bonus tiles if the indicator tile displays a 4. One red 5 tile for each suit is usually used in place of regular five tiles, with some local variants using various amounts (two 5-pin only, two 5-pin and one 5-sō and 5-wan, two of each 5 in all three suits,
et cetera). In some variations, tiles of other numbers such as 3 or 7 can be marked red. • A player cannot win on any discard if any of their potential winning tiles are present in their discard pile. This includes tiles that have been called by other players for open melds. • If a potential winning tile is discarded and the player does not call it to win, that player cannot win on any discard after it until their next turn. This is known as "temporary ". Generally, other players making open melds does not end temporary . • Temporary becomes permanent after ; if a player passes on any chance to win a hand (either passes on a winning discard, or discard a drawn winning tile) after declaring , that player can no longer win on any discard. For the purposes of , potential winning tiles include any tile which would complete the structure of the hand to form four melds and a pair, even if the player could not actually win with that tile due to the resulting hand having no .
Abortive draws In Japanese mahjong, many rules allow abortive draws to be declared while tiles are still available. They can be declared under the following conditions: • , shortened from : On a player's first turn when no meld has been called, if a player has nine different terminal (also known as major) or honor tiles, the player may declare the hand to be drawn. For example, the hand may be . Instead of declaring a draw, the player could choose to go for the
thirteen orphans () hand. • : On the first turn without any meld calls, the hand is immediately drawn when all four players discard the same wind tile. • , or : If all four players declare a ready hand, the hand is drawn after the last player discards without dealing in. • : The hand is drawn when a winning hand cannot be made from the discard after the fourth quad is called, unless all the four quads were called by a single player. If the four quads were collectively called by two or more players, the game may end upon the last player to make a quad discarding (either safely or dealing in), or it may end immediately. If all four quads were called by a single player, the hand continues. Once four quads have been made and the game is allowed to continue, generally, a fifth quad is unable to be formed. Like most optional settings, it is possible that a local mechanism is in place to allow for further quads, but is very rare. ====== Players may be
penalized under the following circumstances: • and : calling respectively or with an invalid hand • Declaring a closed after if the changes the player's waits • : calling while • : calling while not in • and : having more or fewer tiles than allowed (depending on the rules) • : damaging the wall to the point that it cannot be recovered ==Game ending conditions==