Chiitoitsu
Chii toitsu, also known as chii toi or nico nico, 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.
| Type | Yaku |
|---|---|
| Kanji | 七対子 |
| English | Seven pairs |
| Value | 2 han (Closed only) |
| Speed | Medium |
| Difficulty | Medium |
Tile diagram
Winning tile:
Fu
By default, this hand is always given 25 fu. In addition, a chii toitsu 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 chii toitsu hands. Although, the 25 fu column is equivalent to 50 fu numbers.
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 toi toi is actually a slower developing hand in this instance. This is especially the case, when the potential chii toitsu hand sits at iishanten; and it may actually be recommended to let the hand develop into a chii toitsu tenpai.
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 toi toi hand, san ankou, or even suu ankou. 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.