Chiitoitsu
Chiitoitsu 「七対子」, also known as chiitoi or niconico, is one of the standard yaku hands. This hand consists of seven pairs. Under most rulesets, no two pairs may be identical. However, certain house rules may allow duplicate pairs. This hand is one of the two exceptions of the "four melds and one pair" rule of forming a hand, where the other exception is the kokushi musou. This hand is closed only.
| Type | Yaku |
|---|---|
| Kanji | 七対子 |
| English | Seven pairs |
| Value | 2 han (Closed only) |
| Speed | Medium |
| Difficulty | Medium |
Tile diagram
Winning tile:
Development
Given the number of pairs in this hand, it is often tempting to call pon to turn pairs into triplets. However, toitoi is generally slower if you do not have any ankou (triplets) yet. This is especially true when the potential chiitoitsu hand sits at iishanten, where it is usually best to reach a chiitoitsu tenpai. Tenpai for chiitoitsu always uses the wait of tanki (pair wait) in order to complete the seventh and last pair for the hand.
Nevertheless, transition to other yaku may be favorable if the hand develops at least one ankou. In this case, players may find themselves looking to develop a toitoi hand, sanankou, or even suuankou. Whatever the case may be, this consideration takes some discretion, particularly when taking into account the number of tiles available, current point standing, and/or number of tile draws remaining.
Also, note that the pairs must be distinct; having four of the same tile does not count as two pairs. Some house rules do allow four-of-a-kind to count as two pairs, though. But even in these rulesets, a call for "kan" is not allowed, since a kan is considered as a triplet with an extra tile.
Hand interpretation
Unlike most mahjong hands, chiitoitsu is an exception to the "four groups and a pair" pattern. Instead, tiles are groups into pairs or toitsu. As such, the tile groupings cannot be interpreted other ways. For this reason, chiitoitsu is also granted a unique fu count of 25, which remains static.
Shanten
The shanten count for chiitoitsu is simpler to count, which can be marked by the number of pairs in the hand.
| Shanten | Pair count | Hand | Comment |
|---|---|---|---|
| Tenpai | 6 |       |
Obvious choice for chiitoitsu while in tenpai or 1-shanten. The choice of riichi will depend on the waiting tile, current hand, and current score.
A 1-shanten hand waits to pair one of three tile types for tenpai. Upon attaining tenpai, one of the three must be discarded. |
| 1 | 5 |
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| 2 | 4 |  |
A hand with four pairs may consider for chiitoitsu. Only one more pair is needed to get to 1-shanten. |
| 3 | 3 |  |
A hand with three pairs is very inefficient. |
| 4 | 2 |  |
Attempting chiitoitsu with this start is very unreasonable. If anything a hand of this composition is better off utilizing other yaku. |
| 5 | 1 |
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Acquiring ankou
For chiitoitsu, the hand has numerous pairs during development. One of the pairs may develop into a triplet. This may encourage a player to develop the hand for toitoi, sanankou, or even suuankou.
Compatibility
^ Ippatsu requires riichi to be of any use.
| RCH | DRI | IPP | SMO | TAN | PFU | IPK | ITT | YAK | SDJ | SDO | TOI | SNA | SNK | CHA | JUN | RPK | SSG | HRO | HON | CHN | CHI | RIN | HAI | HOU | CHK | |
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The composition of this yaku makes it very restrictive regarding its combination with other yaku. Chiitoitsu cannot be combined with any yaku dependent on tile groups of three, as this yaku consists of only pairs. Chiitoitsu combined with chanta gives honroutou, and it cannot be combined with junchan as there are only six different terminals, but chiitoitsu requires seven distinct pairs.
This yaku forbids kan, so rinshan is incompatible. Chankan is also incompatible. A hand in tenpai for chiitoisu always has a copy of the winning tile, thus making it impossible for other players to make the added kan call required for chankan.
With iipeikou or ryanpeikou
A chiitoitsu hand may collect sequential series of paired tiles, which may look like iipeikou or even ryanpeikou. Both yaku are incompatible with chiitoisu, as once again, all tiles are considered to be in pairs, not sequences.
Value
As a special exception to the usual scoring rules, this hand is always given 25 fu. No other fu are awarded: not for yakuhai pairs nor for tanki waits. The value is not rounded up to 30 fu. This produces a unique set of scoring values for chiitoitsu hands at a given han value, although the point values are the equivalent of the 50 fu numbers. Like all hands, once a chiitoitsu hand is valued at 5 han or more, then it is counted for mangan or greater. Chiitoitsu with mentsumo produces a 3-han hand. Since chiitoitsu can only occur in a closed hand, it is not possible to produce a 2-han chiitoitsu hand by tsumo.
| Position | 2 han | 3 han | 4 han | 5 han or more |
|---|---|---|---|---|
| Non-dealer tsumo Non-dealer ron |
Not possible 1600 |
800/1600 3200 |
1600/3200 6400 |
Mangan, Haneman, etc. |
| Dealer tsumo Dealer ron |
Not possible 2400 |
1600 4800 |
3200 9600 |
High scoring chiitoitsu hands are possible without dora. The highest possible involves riichi, ippatsu, tsumo, haitei and chinitsu. With the 2 han for chiitoitsu, the combination brings the hand to a whopping 12 han. Note that tanyao cannot be added, as the hand 22334455667788 can be scored as ryanpeikou and pinfu for an additional 2 han over chiitoitsu. In some rule variations, this hand is an optional yakuman, known as "daisharin", "daichikurin", or "daisuurin", depending on the suit.
With dora
All tiles in this yaku must be in pairs. Therefore the dora tiles also occur in pairs. If dora is involved, then at minimum, this yaku may possess at least 2 dora. The notable exception are the red dora, if used, which appear as individual reds in their own right.
External links
- Chiitoitsu in Japanese Wikipedia