Ryanmen
Ryanmen 「両面」, sometimes called an "open wait" in English, is the most common wait pattern in the game. It involves two consecutive numbered tiles, waiting on either "outside" number. For example, a "34" needs either a 2 or a 5 in order to form a sequence of either 2-3-4 or 3-4-5. A ryanmen cannot be formed with terminal tiles. It is, by far, the most efficient wait pattern: it waits for 8 tiles (of two types) while only requiring 2 tiles in hand.
| Kanji | 両面 |
|---|---|
| English | Open wait |
| Fu | 0 fu |
| Tile types waiting | 2 sided wait |
| Tiles available | 8 tiles |
| Pattern example |
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| Tenhou.net example | Using riichi |
Pattern
Waiting for: 
or 
Ryanmen always waits for two tiles.
Fu
Due to its relative ease, a ryanmen wait is not awarded any fu.
As it lacks fu, a ryanmen wait is required for pinfu. To score pinfu, you must have a ryanmen (or a complex wait which can be interpreted as ryanmen), as all other waiting patterns end up scoring fu.
Usage
Ryanmen is the most frequent wait in the game, due to its strength and ease of creation. Approximately 50% of all tenpai hands, and 66% of all riichi hands, use a ryanmen wait.
- It is the most powerful of the basic waits. A ryanmen waits for a maximum of 8 tiles of two different types. All other basic wait patterns can wait for a maximum of 4 tiles - ryanmen is twice as big.
- Unlike complex waits, ryanmen only requires two tiles to form. Therefore, ryanmen is much more likely to form than a complex wait.
- Pinfu, a common yaku, requires a ryanmen or ryanmen-derived wait.
Whether a hand is in tenpai or not, ryanmen waits are efficient to gather and use.
Suji
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Suji (i.e. the "mahjong intervals") is a defensive concept directly related to ryanmen waits.
In essence, when a tile is suji, it would be impossible for an opponent to have a ryanmen wait without being in furiten.
- A ryanmen will always wait on tiles that are three apart, forming the intervals: 1-4-7, 2-5-8, and 3-6-9. For example, a 2-3 ryanmen waits for either a 1 or 4, and is thus part of the 1-4-7 interval.
- Therefore, if an opponent discards a 4, they cannot have a ryanmen wait on a 1 or 7 of the same suit (without being in furiten, which would prevent them from winning off your discarded tile). So after an opponent discards a 4, it is safer to discard a 1 or 7.
- If the opponent discards a 1, then the 4 is not necessarily safe: they could still have a 4-7 ryanmen wait. For 4 to be "full" suji, both 1 and 7 must be discarded.
Suji works because ryanmen is so effective and common.
Related Complex Waits
These complex waits are related to ryanmen waits.
Sanmenchan
Waiting for: 
, , 
When a ryanmen is adjacent to a complete sequence, forming 5 consecutive number tiles, it forms a sanmenchan - which waits for 3 tiles instead of 2. This is because the hand can be interpreted in one of two ways:
ryanmen + 
sequence; Waiting for: 
,
- sequence + ryanmen; Waiting for: ,
This wait pattern never scores fu (and is thus eligible for pinfu), because it is always interpreted as a ryanmen wait.
Ryantan
Waiting for: 
, 
, and
A ryantan is a triplet with another tile that is numerically adjacent, where none are terminal tiles. It is a combination of the ryanmen and tanki waits. Hands that lack another pair can enter tenpai with a ryantan.
It can be interpreted as either "555 + 6" (triplet + tanki wait) or "55 + 56" (pair + ryanmen wait). Thus, it waits on 4m and 7m (completing the ryanmen) as well as 6m (completing the tanki). Ryantan scores fu only if it completes the tanki wait. When completing the ryanmen wait, it scores no fu, and is thus eligible for pinfu.