Kanchan
Kanchan 「嵌張」 is a wait pattern that completes with the middle number of a sequence.
| Kanji | 嵌張 |
|---|---|
| English | Closed wait, Middle wait |
| Fu | 2 fu |
| Tile types waiting | 1 sided wait |
| Tiles available | 4 tiles |
| Pattern example |
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| Tenhou.net example | Kanchan |
Pattern
Fu
Kanchan is awarded 2 fu upon winning. A closed hand winning by ron automatically becomes mangan, if it scores 4 han.
Strategy
Kanchan is considered to be a "bad wait", because it can only wait for a maximum of 4 tiles. Thus, they are worse for hand development. Like the other bad waits, kanchan can be used to suji trap opponents.
In general, inner kanchans > outer kanchans > penchans when it comes to tile efficiency. See below for details.
Kanchan vs Penchan
While kanchan and penchan wait on the same number of tiles, a kanchan is considered better to keep. This is because kanchans are easier to upgrade.
- A
kanchan can be upgraded by drawing 
, turning it into a (two-sided) ryanmen.
- A
penchan cannot be upgraded to ryanmen on its own. It must first draw a , turning it into a kanchan, then draw the to get a ryanmen.
As a kanchan requires 1 tile to be upgraded to a ryanmen, but a penchan requires 2 tiles, the kanchan is superior to keep before tenpai. In addition, only a kanchan can be turned into a ryankan shape (see below section), giving another advantage to kanchan. However, once you reach tenpai, both kanchan and penchan become effectively identical.
Inner vs Outer Kanchan
There are two different types of kanchan: inner and outer.
| Type | Tiles | |||
|---|---|---|---|---|
| Inner |   |
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| Outer |  |
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Inner kanchans are generally superior to outer kanchans because they are easier to upgrade, similar to how (all) kanchans are better than penchans.
- A
kanchan can be upgraded by drawing (turning into ) OR 
(turning into ). It can also be turned into a ryankan when drawing either or 
.
- A kanchan can only be upgraded by drawing . It can be turned into a ryankan when drawing only.
Note that an inner kanchan waits on a middle tile. Middle tiles are harder to win with, so there's some downside to using them.
Ryankan
A ryankan is an extended form of a kanchan, only available before reaching tenpai. A ryankan shape is composed of three tiles that are each 2 apart, such as:
| Pattern | |
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|---|---|---|---|
| Tiles to complete | |
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A ryankan is effectively the same as having 2 different kanchan waits; it waits for 8 tiles of two types (4 tiles per type).
However, you cannot enter tenpai with a ryankan. If you would reach tenpai without completing the ryankan, you'd have to discard one of its three tiles, turning it back into a weak kanchan wait.
Example hand with ryankan shape:
With the example hand above, if you drew , you would have to discard either or to enter tenpai. You end up with a bad wait, but with one major advantage - a ryankan always forms a suji trap. Here, if you discarded the 6s, you would wait on the suji 3s, thus making it more likely for others to deal in. This is why a suji of the riichi declaration tile is considered more dangerous.