Dora
Dora 「ドラ」 are special tiles; each dora in your hand grants 1 han. However, hands still require at least one yaku in order to score. Dora do not count towards the yaku requirement, so they are best considered as a bonus.
At the beginning of every hand, fourteen tiles are set aside as the dead wall tiles. One dead wall tile is then flipped over. The tile sequentially after the flipped tile is considered dora. Additional dora may be revealed through kan, known as kandora. Also, hands that declare riichi may score extra uradora.
Dora Indicators
Every time tiles are dealt, fourteen tiles are set aside to form the dead wall, or wanpai 「王牌」. One of these tiles - the third from the initial wall break, as shown in the picture - is always flipped over to indicate the dora. The tile sequentially after the flipped "dora indicator" is the dora itself. For example, if 1-man is the dora indicator, then 2-man is the dora itself.
The following lists the complete dora order. Note that the order loops around, and that doras do not "cross-indicate" tiles of another suit.
Suit order
If the dora indicator is , then the dora is .
If the dora indicator is , then the dora is .
If the dora indicator is , then the dora is .
Wind order
If the dora indicator is , then the dora is .
The wind order follows the same order as the seat winds in the same counter-clockwise direction as the normal turn order.
Dragon order
If the dora indicator is , then the dora is .
Multiple Dora
Dora stack; a hand can have as many dora as it can fit into the hand.
In the event a dora indicator is repeated, then the dora tile will be worth one han per dora indicator.
Examples:
- Dora indicators
A single 
is worth 2 han.
- Dora indicator
A single 
is worth 2 han - one as a regular dora, one as an akadora.
Other types of dora
During the game, you may find additional sources of dora.
Kandora
After a call for kan, an additional dora indicator is flipped. Specifically, the tile next to the dora indicator counter-clockwise on the dead wall is flipped. These are known as kandora 「カンドラ」.
Casual games will simply flip the kan dora immediately after kan. Others will differentiate between the kan types.
- Open kans (both damiminkan and shouminkan) only reveal the dora indicator after a discard, or after the next kan.
- Closed kans (ankan) reveal the dora indicator immediately.
Uradora
Uradora 「裏ドラ」, or underneath dora, are used whenever a hand wins with riichi. Therefore, no open hand may ever have access to the ura dora. In the event that any riichi-declaring hand wins, the tiles underneath the dora indicator(s) are revealed. These newly revealed tiles serve as additional dora indicators.
For each kandora revealed, the hand gets an additional uradora indicator. These are known as kanuradora 「カン裏ドラ」.
Akadora
Akadora 「赤ドラ」, akapai 「赤牌」, or red dora are tiles marked in red. Unlike dora indicators, having the red tile itself in your hand counts as a dora.
Akadora are frequently included in games, but are not universal. The most common rule is to include three red fives, one of each suit.
Most modern mahjong sets will include an extra red 5p (in total: two red 5p, one red 5m/5s). Sets may include other tiles marked "red" as automatic dora. Five happens to be the common choice because it is the center number within the 1 through 9 range. Though rarely found, some older sets include a "red haku" tile (white dragon), with some marking not present on the usual haku tile, and some sets include red threes.
An akadora used as a dora indicator is treated as a regular tile.
Nukidora
In some rules of three-player mahjong, the North tile may be used as a special dora. When a North tile is obtained, the player may call kita, set the tile aside, and the hand gains 1 nukidora. Then, the player gets a dead wall draw. North tiles not called for kita are not dora.
Strategy
Dora tiles are valuable due to their +1 han. Until mangan, each han will roughly double your score, so even one dora is a substantial score boost.
Because of their value, the dora itself, as well as tiles around the dora, are generally more dangerous to discard.
Rule variations
Rules variations differ on the use of dora.
- The initial dora is the most common - it is generally universal within Japanese mahjong.
- Kandora and uradora may be excluded in some rulesets, but it is common to use both.
- Akadora is the most optional, with many rules enabling/disabling them. Mahjong tile sets are often sold with red fives in addition to four regular fives of each suit.
External links
- Dora in Japanese Wikipedia