Chiitoitsu: Difference between revisions

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 [[Shanten|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.

Unlike most mahjong hands, chiitoitsu is an exception to the "four [[Mentsu|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.  

The composition of this yaku makes it very restrictive regarding its combination with other yaku. Chiitoitsu cannot be combined with any yaku dependent on [[mentsu|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.

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.

High scoring chiitoitsu hands are possible without dora. The highest possible involves [[riichi]], [[ippatsu]], [[menzenchin tsumohou|tsumo]], [[haitei raoyue and houtei raoyui|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#Daisharin|rule variations]], this hand is an [[optional yaku|optional yakuman]], known as "daisharin", "daichikurin", or "daisuurin", depending on the suit.

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, [[Dora_variations#Akadora|if used]], which appear as individual reds in their own right.