|Tile types waiting||5 sided wait|
|Tiles available||13 tiles|
Tatsumaki 「竜巻」 is a tile wait pattern that uses a combination of ryanmen, shanpon, and tanki waits to create a hand waiting on 5 consecutive tiles in the same suit. This is a particularly powerful waiting pattern as it relies on only seven tiles in the concealed portion of the hand, so even with two called tile groups, the hand can have a 5-sided wait.
To determine the waiting tiles, a player must rely on the basic wait patterns. One ryanmen wait looks for 3-pin and 6-pin. Another ryanmen waits for 4-pin and 7-pin. Finally, a tanki wait is aiming for a 5-pin. The shanpon wait overlaps the ryanmen waits, as it goes for the 4-pin or 6-pin.
The pattern is always composed of two sets of numbered triplets. The numbers of these triplets must be two away from each other, such as 4 and 6 from the example. The two sets of triplets are connected by a single numbered tile inbetween the two numbers. In this case, it is 5. If one of the triplets happen to consist of terminals, the pattern is still a tatsumaki. However, the number of possible waiting tiles is reduced.
This pattern generates 2fu for a tanki wait only if it is won with the middle tile. Winning with any of the four other tiles will not give any fu, as it will be interpreted as a ryanmen wait. If interpreted for shanpon, then fu is generated based on the tile composition.
- Tatsumaki in Japanese Wikipedia