Beginner's Lesson 9
Triplet and Pair-based Yaku
In this lesson, we will review 1 more yaku from Mahjong Lite and introduce another 3 yaku.
The first yaku is toitoihou, usually shorted to “toitoi”. Toitoi requires all 4 sets in the hand to be triplets, meaning that none of them can be sequences. This is the same as it was in Mahjong Lite, but it is much more difficult to complete 4 triplets than 2. In practice, this is done by calling other players’ tiles, which we will cover in a later lesson. Toitoi is worth 2 han.
The second yaku is san ankou. San ankou requires 3 concealed triplets (“ankou”). For a triplet to be considered an ankou, the entire triplet must be drawn by the player; they must not have called another player’s tile to complete that triplet, even by ron. San ankou is worth 2 han.
The third yaku is sanshoku doukou. This is similar to sanshoku doujun, except that instead of the same sequence across all 3 suits, it is the same triplet across all 3 suits. For example, having a triplet of 5pin, 5sou, and 5man would qualify a hand for sanshoku doukou. Sanshoku doukou is worth 2 han.
The last yaku is chiitoitsu. Chiitoitsu is a special type of hand that does not follow the usual 4 sets and a pair pattern. Instead, chiitoitsu requires the hand to be 7 pairs. In practice, that means that the hand has 6 pairs and is waiting to pair up a 7th tile to win. Under most rulesets, all 7 pairs must be different; you cannot have 4 of the same tile for chiitoitsu. Chiitoitsu is worth 2 han, but uses a slightly different scoring system from normal hands. This will be covered in a later lesson.
Here is a video explaining these yaku by Light Grunty:
Toitoi, San Ankou, and Chiitoitsu
When making a hand with toitoi and/or san ankou, it is very possible to use yakuhai to increase the score of the hand. It is also possible to combine all 4 of these yaku with tanyao.
In the next lesson, we will review the last yaku from Mahjong Lite, chanta, and its related yaku.