Ittsu
Last updated: 2026-08-18Ittsu requires 123, 456, and 789 sequences in one suit — a full straight. 2 han closed; 1 han open. See Riichi Mahjong Yaku Guide.
Requirements
- One suit has all three sequences: 123, 456, and 789
- 2 han closed; 1 han open
- vs Sanshoku: ittsu is vertical (one suit); sanshoku is horizontal (three suits)
Valid example
Man 123·456·789 — ittsu (2 han closed). Ron on 3 sou completes the hand.
Invalid or confusing
Man, pin, and sou each have 123 — sanshoku, not ittsu (missing 456 and 789 in one suit).
Stacking and open hands
Open play loses 1 han. Can stack with tanyao, pinfu, etc. Often built by concentrating tiles in one suit.
Scoring
Fu follows normal rules; with pinfu, pair and wait matter. See Fu Calculation Basics.