Ittsu
一気通貫 | Ikki Tsuukan
Complete a full straight of 1 through 9 in a single suit using three sequential melds.
By Kenji Tanaka · Updated
Overview
Ittsu, the pure straight (also called ikkitsuukan), is a yaku worth 2 han closed and 1 han open, earned when you hold the full 1-through-9 run of a single suit split across three sequences: 1-2-3, 4-5-6, and 7-8-9 all in the same suit. It rewards committing a large part of your hand to one suit's complete range, and it pairs naturally with pinfu, honitsu, and chinitsu within that suit. The difficulty is that filling all three sequences in one suit ties up many tiles and can leave narrow waits, so players usually pursue ittsu when a starting hand is already heavy in one suit. Because it keeps value when opened, ittsu is also a reasonable target for calling hands. A closed ittsu boosted by dora, or combined with honitsu, can reach haneman, making it a satisfying mid-to-high level goal that turns an ordinary one-suited hand into a strong score.
Example Hand
123m 456m 789m 55p 67s
Conditions
- The hand must contain 1-2-3, 4-5-6, and 7-8-9 as three separate sequence melds, all in the same suit
- The remaining meld and pair can be anything
- Worth 2 han when the hand is closed, 1 han when open
- The three sequences must use tiles from a single suit (all characters, all circles, or all bamboo)
Strategy Tips
- When you already have two of the three required sequences in one suit, prioritize completing the third. The middle sequence (4-5-6) is usually easiest to complete since those tiles have the most flexibility.
- Ittsu combines well with honitsu or chinitsu since you are already committing heavily to one suit. Adding honor tiles alongside can build toward honitsu.
- Ittsu keeps its value when opened (dropping from 2 han to 1), so calling chii to complete the straight is a legitimate speed play. Just weigh what the call costs first: opening the hand gives up riichi, menzen tsumo, and any ura dora, which is often worth more than the han you keep.