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 |
  |
| 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.
Ryankan
A ryankan is an extended form of a kanchan. A ryankan shape is composed of three tiles that are each 2 apart, such as:
Tiles to complete| Examples |    |
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|---|---|---|---|
| |
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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 the three tiles, turning it back into a weak kanchan shape.
Example hand with ryankan shape:
With the example hand above, if you drew 
, you would have to discard either or to enter tenpai. This has one major advantage - a kanchan wait is always a suji trap. Here, if you discarded the 6s, you would wait on the suji 3s, making it more likely for others to deal in.
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, 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. This is similar to how (all) kanchans are better than penchans, as kanchans are easier to upgrade.
- A
kanchan can be upgraded by drawing (turning into ) OR 
(turning into ). It can also be turned into [[
- A kanchan can only be upgraded by drawing .
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.