Riichi Mahjong · Closed 2 / open 1
Ittsu (Pure Straight) in Riichi Mahjong: Han, Examples and Tips
In riichi mahjong, Ittsu (ikkitsuukan, pure straight) is worth 2 han closed and 1 han open: three sequences , and in one suit, running straight from 1 to 9. You can call for it, but it drops one han.
On this page
The rules for Ittsu
- 1-2-3, 4-5-6 and 7-8-9 in the same suit: characters, dots or bamboo
- It has to be exactly those three: a run like , , doesn't count
- The fourth set and the pair can be anything
- Chi and pon are allowed, but it drops a han when open: 2 han closed, 1 open
How Ittsu waits
Usually one of the three sequences is missing. If the gap is (waiting on ) or (waiting on ), it's a two-sided wait — but only one side completes the ittsu.
How Ittsu is scored
The yaku, han, fu and points below are computed live by the same scoring code the game uses.
Ron
| Pinfu | 1 han |
| Ittsu | 2 han |
| Total | 3 han 30 fu · 3,900 points |
|---|
Non-dealer, East round, no dora, no honba.
Ron
| Ittsu | 1 han |
| Total | 1 han 30 fu · 1,000 points |
|---|
Non-dealer, East round, no dora, no honba.
Ron
| Yakuhai: seat wind | 1 han |
| Ittsu | 1 han |
| Honitsu | 2 han |
| Total | 4 han 30 fu · 7,700 points |
|---|
Non-dealer, East round, no dora, no honba.
Common combinations:
| Combination | Han |
|---|---|
| Ittsu (closed) | 2 |
| Ittsu (open) | 1 |
| Riichi + pinfu + ittsu | 4 |
| Ittsu + honitsu (open) | 3 |
| Ittsu + honitsu (closed) | 5 |
| Ittsu + chinitsu (closed) | 8 |
How it relates to other yaku
- Sanshoku: the other 2-han closed sequence yaku, which needs three suits; it can't appear together with ittsu.
- Honitsu, chinitsu: ittsu already uses nine tiles of one suit; if the other five are the same suit (or honors), it becomes a flush and the han jump.
- Pinfu: ittsu is three sequences, so a closed two-sided wait often brings pinfu too.
- Never with tanyao: ittsu always contains a 1 and a 9.
Ittsu odds
Ittsu needs nine tiles of one suit in a straight line, so it's rarer than sanshoku. When the computers on this site play normally, ittsu is part of 0.57% of all wins; 33% of those were called, and ittsu wins average 9,100 points.
| 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 Ittsu
- Two of the three sequences already in one suit: with and , watch , and .
- Lots of one suit: ittsu plus honitsu or chinitsu is a classic route to a big hand.
- You haven't thrown away the 1 or 9: ittsu needs both, so cutting them early ends it.
- When to call: open it's only 1 han. Calling is fine together with honitsu; for ittsu alone, aim for a closed riichi.
To practice, open a table of free online riichi mahjong — the computers play with you and count the points.
Ittsu in other mahjong styles
Chinese Official (Guobiao) calls it "Pure Straight", 16 fan, with no drop when called (Guobiao fan table). Taiwanese and Hong Kong mahjong have no matching hand.
FAQ
How many han is Ittsu?
2 han closed, 1 han after a chi or pon.
Does 2-3-4, 5-6-7, 7-8-9 count as Ittsu?
No. It has to be exactly 1-2-3, 4-5-6 and 7-8-9, all in the same suit.
Can Ittsu and Sanshoku both count?
No. Both need three sequences, one in a single suit and the other across three suits — a hand doesn't have enough sequences for both.
Related yaku
Sanshoku Closed 2 / open 1
The same sequence in all three suits — 2 han closed, 1 open. Examples, common combos and how to spot a sanshoku chance.
Honitsu Closed 3 / open 2
One suit plus honors — 3 han closed, 2 open. Examples, honitsu vs chinitsu, and how many tiles you need to go for it.
Chinitsu Closed 6 / open 5
Every tile from one suit — 6 han closed, 5 open. Examples, chinitsu vs honitsu, and how many suited tiles you need.
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.