Chiitoitsu

Chiitoitsu

Type	Yaku
Kanji	七対子
English	Seven pairs
Value	2 han (Closed only)
Speed	Medium
Difficulty	Medium

Chiitoitsu, also known as chiitoi or niconico, is one of the standard yaku hands. This hand consists of seven pairs, where no two pairs may be identical. In other words, every pair must be distinct. 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.

Tile diagram

Winning tile:

Value

By default, this hand is always given 25 fu. In addition, a chiitoitsu tenpai always uses a tanki machi (wait). Normally, that wait pattern is awarded 2 fu but not in this case. Finally, the 25 fu number is not rounded up to 30 fu. In turn, the scoring table produces an independent set of point exchanges applied to chiitoitsu hands. Although, the 25 fu column is equivalent to 50 fu numbers.

High scoring chiitoitsu hands are possible without dora. The highest possible involves riichi, ippatsu, tsumo, tanyao, and chinitsu. Add the 2 han for chitoitsu, this combination brings the hand to a whopping 12 han. Then add haitei or houtei, then such a hand becomes a kazoe yakuman. The hand 22334455667788 pinzu contains chiitoitsu, but it's more advantageous to count it as ryanpeiko and pinfu. In some rule variations, this hand is an optional yakuman, known as "daisharin".

With dora

Main article: Dora

Since all tiles in this yaku must be in pairs, then dora tiles also occur in pairs. If dora is involved, then at minimum, this yaku may possess at least 2 dora. The notable exception stems from the use of red dora, which appear as singles in their own right.

Formation

Given the number of pairs in this hand, it is often tempting to call pon with matching discards to the pairs. However, it is generally noted that toitoi is actually a slower developing hand in this instance. This is especially the case, when the potential chiitoitsu hand sits at iishanten; and it may actually be recommended to let the hand develop into a chiitoitsu tenpai, rather than forcing toitoi.

Nevertheless, transition to other yaku may actually 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 does take some discretion, particularly when taking into account the number of tiles available, current point standing, and/or number of tile draws remaining.

Compatability

Main article: Yaku compatability

^ 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

CHI

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 the yaku demands, all tiles must be in pairs.

As for rinshan and chankan, this yaku may combine with neither. Rinshan requires a call of kan, but that is not allowed with chiitoitsu. A player may draw all four of a specific tile, but they are not treated as distinct pairs. For chankan, all chiitoitsu tenpai hands utilize tanki, or single tile wait. In order to win with a chiitoitsu hand, that single tile must be paired, and it is physically impossible for it to be used for an added kan call.

External links

• 七対子

Chiitoitsu in Japanese Wikipedia