Chiniisou
Chinitsu (清一色) is a standard yaku. This yaku is composed of tiles in one suit only. Chinitsu is worth 6 han, but it decreases to 5 han when opened.
Tile patterns
Using pinzu:
Agari: or
Using manzu:
Agari: or or or
Using souzu:
Agari: or or or or 
English reference
- Flush
Formation
As defined, this yaku is formed by collecting tiles of one suit. Therefore, tiles not of a particular suit are regularly discarded. As a consequence, a player aiming for a chinitsu may be easily detected via discards alone.
Complex wait patterns
Chinitsu is notorious for developing complex wait patterns. This is due to the homogenous nature of the yaku. Often, the tiles may form long strings of consecutive numbers. Upon doing so, the wait patterns increase in complexity.
Yakuman
Due to the relatively high value of this yaku, chinitsu may be involved in the formation of kazoe yakuman.