Riichi Mahjong · 1 han（closed only）
Iipeikou (Pure Double Sequence) in Riichi Mahjong: Rules and Examples
In riichi mahjong, Iipeikou (pure double sequence) is a closed-only yaku worth 1 han: two exactly identical sequences — same suit, same numbers — such as twice. One call and it's gone, so it's a small bonus for closed hands that usually comes with riichi and pinfu.
On this page
The rules for Iipeikou
- Two sequences, same suit, same numbers: twice counts; plus doesn't (that's heading for sanshoku)
- Closed only: any chi, pon or open kan removes it; a closed kan keeps the hand closed
- The other two sets and the pair can be anything
- Three identical sequences still count as one iipeikou; two different doubled sequences make ryanpeikou
How Iipeikou waits
The typical shape is "one tile short of two identical sequences": with and a pair, drawing completes twice.
How Iipeikou is scored
The yaku, han, fu and points below are computed live by the same scoring code the game uses.
Ron
| Pinfu | 1 han |
| Iipeikou | 1 han |
| Total | 2 han 30 fu · 2,000 points |
|---|
Non-dealer, East round, no dora, no honba.
Ron
| Tanyao | 1 han |
| Total | 1 han 30 fu · 1,000 points |
|---|
Non-dealer, East round, no dora, no honba.
Riichi · Tsumo
| Riichi | 1 han |
| Menzen tsumo | 1 han |
| Pinfu | 1 han |
| Iipeikou | 1 han |
| Chinitsu | 6 han |
| Total | 10 han 20 fu · Baiman · 4,000 / 8,000 points |
|---|
Non-dealer, East round, no dora, no honba.
Common combinations:
| Combination | Han |
|---|---|
| Iipeikou | 1 |
| Riichi + iipeikou | 2 |
| Riichi + pinfu + iipeikou | 3 |
| Riichi + pinfu + tanyao + iipeikou | 4 |
How it relates to other yaku
- Ryanpeikou: two iipeikou in one hand, 3 han; it replaces iipeikou rather than adding to it.
- Chiitoitsu: is also three pairs. A ryanpeikou shape is also a seven-pairs shape, and the higher score is used.
- Pinfu, tanyao: iipeikou is made of sequences, so it fits these shapes and they often come together.
- Sanshoku: the same sequence in three suits; iipeikou is the same sequence twice in one suit — a different yaku.
Iipeikou odds
You rarely plan iipeikou; it appears when you draw a duplicate tile and keep it as a second sequence. When the computers on this site play normally, iipeikou is part of 2.4% of all wins, and those wins average 10,600 points. The share is low partly because iipeikou needs a closed hand and the computers often call for speed.
| Yaku | Share of wins |
|---|---|
| Riichi | 46% |
| Menzen tsumo | 22% |
| Yakuhai | 40% |
| Tanyao | 19% |
| Pinfu | 12% |
| Ippatsu | 8.9% |
| Chiitoitsu | 3.7% |
| Iipeikou | 2.4% |
| Sanshoku doujun | 1.6% |
| Honitsu | 0.76% |
| Ittsu | 0.57% |
Source: 40,000 computer hands on this site (all four at normal level), 33,226 wins. A win usually has several yaku, so the shares add up to more than 100%.
Which hands suit Iipeikou
- Doubled runs like or : one more tile gives two identical sequences.
- Closed and on the way to tenpai: iipeikou can't be called, so if it's in reach, don't call — reach tenpai and declare riichi.
- When choosing a discard: in , the can serve the iipeikou or the pair, so it's worth more than an isolated terminal.
To practice, open a table of free online riichi mahjong — the computers play with you and count the points.
Iipeikou in other mahjong styles
Chinese Official (Guobiao) has "Pure Double Chow" (the same sequence twice in one suit) for 1 fan, and it may be called (Guobiao fan table). Taiwanese and Hong Kong mahjong have no matching hand.
FAQ
How many han is Iipeikou?
1 han, closed only. Any chi or pon removes it.
Does Iipeikou stack with Chiitoitsu?
No. Chiitoitsu is the special seven-pairs shape, while iipeikou belongs to the normal four-sets-and-a-pair shape; only the higher-scoring reading is used.
What about three identical sequences?
Three identical sequences (say three times) can also be read as three triplets , and ; the scoring compares both readings and keeps the higher one. Read as sequences, it's just one iipeikou.
Related yaku
Ryanpeikou 3 han（closed only）
Two iipeikou, closed only, 3 han. Examples, the difference from chiitoitsu, combos and how rare it is.
Pinfu 1 han（closed only）
Four sequences, a non-value pair and a two-sided wait — closed only, 1 han. Waits, 20 vs 30 fu, common combos.
Chiitoitsu 2 han（closed only）
Seven different pairs, closed only, 2 han 25 fu. Examples, picking your wait, combos, and how many pairs make it worth it.
Try it at the table
Riichi Mahjong — Play Japanese Riichi Mahjong free in your browser against three AI opponents. Standard online rules with red fives, ippatsu and ura dora, a yaku guide, wait and furiten hints, and three AI levels. No sign-up.