Ryanpeikou

Ryanpeikou 「二盃口」 is a standard yaku, consisting of two "iipeikou". The prefix "ryan" is a Japanese counter for mahjong, signifying for "two".

Ryanpeikou
Type Yaku
Kanji 二盃口
English Two sets of identical sequences
Value 3 han (closed only)
Speed Very slow
Difficulty Very hard

Tile pattern

              Agari:  

Note: This hand may also win with  . However, it'll only count for a lesser value of iipeikou (and pinfu).

Formation

At the very least, the hand must initially qualify for the yaku, iipeikou. With tenpai, the tile wait involves a tanki, to complete the pair, or the need to complete the other "iipeikou".

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
RPK                                                  

Ryanpeikou is incompatible with other yaku that place conflicting requirements on the mentsu in the hand. Ittsu, sanshoku, sanshoku doukou, toitoi, sanankou, sankantsu, and shousangen are excluded as they are require either three different sequences or at least one triplet/quadruplet. Rinshan kaihou also requires a kan, so it is excluded. Chankan is incompatible because the winning tile must be unique in the winning hand---all four copies of it having been used in another player's kan. Finally, iipeikou is incompatible because it is superseded by ryanpeikou.

Chiitoitsu

This yaku does not combine with chiitoitsu. By definition, chiitoitsu is formed by the collection of seven distinct pairs. In most instances of ryanpeikou, the hands look like chiitoitsu hands. However, ryanpeikou is actually composed of sequences, rather than as independent pairs. Because of this interpretation, the two yaku remain distinct and incompatible. It is doubtful that any house rule allows the combination of the two yaku.

Note that not all instances of ryanpeikou look like chiitoitsu. The following, for instance, is a valid ryanpeikou hand:

              Agari:  

With chinitsu

Some forms of ryanpeikou mixed with chinitsu and tanyao may actually form some optional yakuman, named daisharin (pinzu), daichikurin (souzu), and daisuurin (manzu).

              Agari:  ,  , or  

Value

 
Ryanpeikou with real tiles.

Ryanpeikou can only be scored closed, and is always worth 3 han. So there is no need to be concerned about the hand losing value when open. The cheapest ryanpeikou hand uses either a kanchan / penchan / tanki wait, or a ryanmen wait with valued honor as the pair. In both cases, the hand produces a 3-han and 40-fu value by ron. By tsumo, it is 4-han and 30-fu.

External links

Ryanpeikou in Japanese Wikipedia