Ittsu 一気通貫

What It Is

Ittsu (一気通貫, short for ikkitsuukan) is three runs in one suit: 1-2-3, 4-5-6 and 7-8-9. All three runs must be there exactly; 2-3-4, 5-6-7 and 7-8-9 is not ittsu.

The fourth set and the pair are free: any run or triplet in any suit, and any pair at all.

What It’s Worth

Ittsu is 2 han (1 open). It loses a han when open, like the other run-based yaku.

Because it’s made of runs, a closed ittsu often comes with pinfu as well, and riichi on top turns a quiet hand into a real one. In a flush, the han add up fast.

Closed Or Open

A chi doesn’t kill it. Call 7-8-9 to finish the straight and the hand still has ittsu, at the lower value. Closed, with riichi and pinfu, it scores much better.

How To Build It

You need nine particular tiles, so ittsu works best when the deal already gives you six or seven of them in one suit. Hold the gaps open: a 1-2-3 and a 7-8-9 with a 4-6 waits for the 5.

Middle tiles of that suit are precious; ends from other suits go first. If the straight isn’t coming together by the middle of the hand, let it go and keep the runs you have.

Ittsu also works well in a hand that’s already leaning towards one suit. If you’re collecting Circles for honitsu anyway, the straight is often only one or two tiles further, and each of those tiles is one you wanted to keep.

Common Mistakes

• Counting the wrong runs. Nine different numbers isn’t enough; they must split exactly into 1-2-3, 4-5-6 and 7-8-9.
• Edge waits. A 1-2 waiting on 3 is a slow single-tile wait. If you can, build so the last piece is a middle run with two sides.
• Forgetting other suits. A run of 4-5-6 in Bamboo doesn’t help a Circles straight.

What It Combines With

In a one-suit hand ittsu really shines: ittsu with honitsu and a yakuhai set can climb into the limits. Closed, it sits well with riichi and pinfu. It can’t meet sanshoku, tanyao or chanta, because it holds the middle and the ends of one suit.