Kan
Kan 「カン」 is a special tile call. This call forms a tile group of four identical tiles, called kantsu 「槓子」 ("quad").
While it appears as a four-of-a-kind, the tiles used for a kantsu function as a triplet plus one extra tile. Therefore, the group counts towards the triplet-based yaku, such as toitoi and sanankou.
The call for kan comes with special properties:
- For every kan, the player is required to take an extra tile from the dead wall. The drawn tile is called the rinshanpai, or dead wall draw.
- In addition, when declaring kan, a new dora indicator is revealed.
The main benefits of kan are the revealed kan dora, a draw from the dead wall, and a boost to fu count. However, your opponents can also benefit from kan dora, so kan is inherently risky. Therefore, you should assess the situation before you make a kan.
Procedure
Kan works similarly to other tile calls, but it comes with special properties and rules. These rules apply when a player possesses or gains possession of four of the same tile, then the player makes the kan call.
- The player calls "kan".
- The four identical tiles are shown and are set aside, like an open call. Together, the four tiles now count as one tile group.
- Then, a replacement tile is drawn from the dead wall. This acts as the replacement tile to maintain the proper hand size for four groups and a pair.
- If this tile draw completes the hand. then the player may declare a win and claim rinshan kaihou.
- Otherwise, the last tile from the wall is added to the dead wall, so that the dead wall contains 14 tiles at all times.
- If the hand has an additional opportunity to call kan, then the player may do so and invokes another kan process.
- Otherwise, the turn may end by discarding normally.
A special case involves chankan. If the kan call is a shouminkan (added kan), and the added tile is a winning tile for another player, then that player may call ron and win with chankan. This happens before the rinshan draw. Typically, the kandora is not revealed for a chankan.
Kandora timing
The call for kan reveals additional dora in the form of kandora. The timing of this reveal will depend on the rule set:
- The simplest rule is to immediately reveal dora after any type of kan. This rule would place to kan reveal right after step 2.
- Many platforms distinguish between open and closed kans. In these rules, closed kans will reveal the kan dora immediately. Open kans will only reveal kan dora after discarding, or after making another kan (i.e. after either step 6 or 7).
Regarding the timing of the kandora, players will need to consult organizational, tournament, and/or local rules.
Kan types
Kan can occur under three different occasions, meaning there are 3 types of kan:
- All four tile types drawn (Ankan; closed kan)
- Closed triplet with the fourth tile type discarded (Daminkan; open kan)
- Open triplet with the fourth tile type drawn (Shouminkan; added kan)
Ankan
Ankan 「暗槓」, or "closed kan", may be declared when a player draws all four of a tile type. Unlike the other two kan types, ankan does not open the hand.
Ankan may be called during any of a player's turns, with a few exceptions. It may not be called right after a pon or chii call, and may not be called if there is no tiles in the live wall. In addition, during riichi, there are special restricitons (see the Kan during riichi section for more details).
Per rule variation, the kandora indicator is flipped immediately with an ankan call.
An ankan is not be subject to chankan, except against a kokushi tenpai (and only if the rules allow that).
Daiminkan
Daiminkan 「大明槓」, or "open kan", may happen when a player possesses three of a tile type in their hand. When the fourth tile is discarded, the player may claim it and form a daminkan. Upon doing so, the player has opened the hand, if it was not open already. Like pon, this call cannot be made on the last discard of the game.
For daiminkan, most rulesets flip the new dora indicator after discarding, or after another kan is made.
A few rules invoke sekinin barai on a player discarding into the daiminkan. If the kan-declaring player wins off the rinshan draw, the player who allowed the kan would be liable for the entire hand.
Shouminkan
Shouminkan 「小明槓」, also called kakan 「加槓」, or "added kan" in English, may happen when a player had previously called pon to form an open triplet. Upon drawing the fourth tile, the player may add that tile to the triplet to upgrade it to a shouminkan. If the fourth tile was discarded by another player, it cannot be claimed by kan. The kan dora timing is the same as daiminkan.
Players may declare a shouminkan during any of their turns. Therefore, the player does not have to call shouminkan immediately. However, if the player has called pon or chii, the ability to create kan is disabled until the next turn. In addition, you cannot call kan if there is no tiles in the live wall.
Shouminkan is vulnerable to chankan ("robbing a kan"). If another player is in tenpai, and the added tile would complete their hand, that player may call ron immediately after the shominkan declaration. Chankan ends the hand before the kan is completed, therefore, no new kan dora indicator is flipped.
Tile arrangements
Tiles called for "kan" are set aside.
Closed
For ankan, the first arrangement is preferred, but the second arrangement is also acceptable.
Called
Daiminkan are indicated as open tile groups, with the four tiles next to each other and one tile turned to indicate the player it was called from. For daiminkan claims from toimen, or the player across, it does not matter which "middle" tile is turned sideways, as long as it is one of the middle tiles.
Added
Shouminkan are indicated as open tile groups, by stacking the added tile above the rotated tile from the original minkou.
(from kamicha, left)
(from toimen, across)
(from shimocha, right)
Multiple kan calls
If in possession with the proper tiles, a player may call kan more than once consecutively. Theoretically, up to 4 kan calls can be made in one turn.
Draw:
In this example, kan may be called twice in a row after drawing 1-man. Both the 1-man and south may each be called for shominkan before making a discard. Naturally, this must be done one at a time, following the proper procedure for kan.
As for kan dora, this once again depends on the ruleset.
- If a kan dora would be immediately revealed, such as for closed kan, the kan dora is revealed on making the kan.
- If a kan dora would be delayed, such as for an open kan or added kan, a kan dora is revealed after a discard or after the next subsequent kan call.
In the case of the above example, two added kans were called sequentially, but only one kan dora indicator was shown upon winning the hand.
Restrictions
Some restrictions apply to kan calls. The restrictions are based on tile counts and rules pertaining to riichi itself.
Kan during riichi
A player may be allowed to call a closed kan during riichi, depending on the hand's composition. This is subject to rule variation:
- Under most professional rulesets, a player is not allowed to call kan if it would change any possible interpretation of the hand. If, for any winning tile, any of the three identical tiles can be interpreted as part of a sequence or part of the pair, the kan is not allowed. By proxy, the hands winning tiles cannot change.
- Under some rulesets, such as in tenhou.net and Mahjong Soul, an alternative is used: if a kan does not change the hand's possible winning tiles, the kan is allowed. (I.e., changing the hand interpretation is allowed, so long as the waits remain the same.)
- In addition, a newly-drawn tile must be included in the kan; you are not allowed to kan if you had all 4 tiles in hand at riichi declaration (see Example 5).
If a player does declare a kan illegally during riichi, and they call ron or the game goes to an exhaustive draw, then they will be penalized with a chombo penalty for breaking the rule. If a player is not required to reveal their hand, or if another player wins, they will normally not be penalized.
Of course, even if a kan is allowed, players may choose to decline a kan call. While a player can benefit from kan dora (and kan uradora), so will their opponents.
Example 1:
Illegal kan: Legal kan: .
It is not allowed to kan the fours. The manzu tiles may either be interpreted as a 3-4 ryanmen wait and a 4-4 pair, or as a 4-man ankou with a 3-man tanki wait. Overall, the hand waits for 2-5-3 man. A kan call would invalidate the 3-4 ryanmen, turning the hand into just a 3-man tanki. Thus, it is forbidden. It is allowed to kan the west winds, since they would be considered an ankou no matter which tile is won.
Example 2:
Legal kan: or .
In this example, none of the waits are affected by any of the kan possibilities. The waiting tiles are completely unrelated to any of the existing triplets in this hand. Therefore, it is acceptable to call kan during riichi here.
Example 3:
Potentially illegal kan: Illegal kan:
Here, the waits are 457p. A kan on 6p would remove the 7p wait, so it is obviously not permitted.
A kan on the 3p would not change the waits. However, if the hand was won with 4p, the hand could be interpreted as:
In this case, the 3p does not form a triplet, but rather a pair and a part of a sequence. A kan on the 3p would remove this potential interpretation of the hand, and therefore may be forbidden (depending on ruleset).
Example 4:
Potentially illegal kan: or
In this example, a kan declaration does not change the wait, but it does change the possible interpretations of the hand. The pinzu section can be interpreted either as three consecutive triplets or three identical sequences :
- or
In this case, a kan call on any of the pinzus would leave only the three triplets interpretation possible. Thus, any of these kan could be deemed illegal after riichi (depending on ruleset).
Example 5:
Illegal kan:
Here, a kan 
when you draw 
doesn't change waits and preserves tenpai. However it is prohibited even in tenhou.net/Mahjong Soul rulesets.
Last tile
Kan cannot be called after drawing the last tile, as the live wall is empty and so a tile cannot be moved to the dead wall. Part of the kan process requires live tiles from the end of the wall to be transferred to the dead wall. If this is not possible, then kan is not possible.
Tile calls
After taking a discarded tile for pon/chii, a player cannot call kan, even if a player has the tile(s) available in hand to do so. The next opportunity to call kan comes after the next tile draw. This does not apply when a daiminkan is called, as the kan causes a tile to be drawn immediately.
Suukaikan
Suukaikan is an abortive draw that occurs when a total of four kans have been called by at least two players. Once the fourth kan has been made, the hand immediately ends once the kan-declarer discards a tile.
However, if a single player makes four kans by themselves (thus entering tenpai for suukantsu), this draw does not occur. The game continues, giving the player a chance to score the yakuman. What happens depends on the ruleset:
- In many rulesets, the other players are not allowed to call a fifth kan to invoke the abortive draw; the fifth kan is simply not allowed.
- In a few rulesets, a player may call a fifth kan to immediately end the game in a draw.[1] The fifth kan draw happens before chankan and rinshan can happen.
This abortive draw exists due to how the dead wall works. Each time a kan is declared, a tile is drawn from the dead wall. The dead wall is 14 tiles large, with 10 tiles reserved as dora indicators, leaving 4 tiles left for kan calls. After four kans, players would end up drawing from the dora indicators, so the fifth kan is forbidden. So, unless someone is in tenpai for suukantsu, the game ends immediately after the fourth kan, to avoid the issue of "players not being able to declare kan".
If abortive draws are disabled, then players are allowed to call kan until a total of 4 kans have been made, and then be unable to call kan for the rest of the hand.
Yaku
Tiles called for kan are still counted as triplets for triplet-based yaku. For example, a closed kan still counts as a "closed triplet" for sanankou. There are a few yaku that specifically require kan: two relating to the action of kan, and two dependent on kantsu in hand.
Chankan
Chankan is a yaku applied on a shominkan (added kan) declaration. A hand in tenpai for a kan call on a tile added to a called pon may declare ron on that tile.
Rinshan kaihou
Rinshan kaihou is a yaku gained by calling tsumo on the replacement tile after any type of kan declaration.
Sankantsu and suukantsu
Both sankantsu and suukantsu require kan calls in order to count. The first requires three calls, while the latter calls for four. Both are rather difficult due to this requirement. Sankantsu is not a yakuman, but some yakuman are actually easier to attain. Suukantsu is by far the most difficult and most rare yakuman to attain.
Kan risks
The nature of kan dora makes the call for kan inherently risky. With this in mind, some quick assessment is needed before making such a call.
References
External links
- Kan in Japanese Wikipedia
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