Ikkitsuukan
ittsu, or ikkitsukan, is one of the standard yaku. This hand consists of three melds in one suit of 1 through 9, any available extra meld, and any pair. This hand may be open or closed.
Tile diagram
Winning tile: 
or 
Open
Winning tile:
English reference
- Straight
Usage
While the hand shows a complete 1-9 grouping from a particular suit, it is best to view as three separate groups of: 123, 456, and 789. This is particularly useful to note when needing to open the hand with such a combination.