Chinroutou

Chinroutou 「清老頭」 is a yakuman, where every tile is a terminal, or 1's or 9's. No other tile type are used: no simples (2-8) or honors.

Chinroutou
Type Yakuman
Kanji 清老頭
English All terminals
Value Yakuman
Speed Very slow
Difficulty Very hard

Tile pattern

               Agari:   or  

Routouhai

Routouhai 「老頭牌」 are the tiles numbered 1 or 9, among the numbered suits. In English, they are denoted as terminals, because they are at the end of the 1 to 9 number scale as the numbered suits do not loop. So a tile group such as 9-1-2 does not count, when it comes to forming tile groups. The terminals are as follows:

      

Formation

For this yakuman, there are only six types of terminals available: two from each of the numbered suit (1 and 9). Simply, no other tile type can be used for this yakuman. Given the basic hand pattern of four melds and a pair, five out of the six types of terminals are needed to build this hand. Since there are only six tile types available for this hand, it is impossible to form a chiitoitsu variation.

Viability

Aside from needing five out of the six terminal types, every tile group must be triplets. Any calls for kan are acceptable too. So, any attempt at this yakuman require the proper number of terminals as well as the ability to collect triplets. More often than not, players must make tile calls in order to do so. Only a rare number of times can this yakuman be completed while closed. On the other hand, the yakuman is rendered impossible if enough terminals are discarded or made unavailable.

External links

Chinroutou in Japanese Wikipedia
Tournament Chinroutou