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.

Chiniisou
Type Yaku
Kanji 清一色
English Flush
Value 6 han (closed)
5 han (open)
Speed Slow
Difficulty Medium

Tile patterns

Using pinzu:

              Agari:   or  

Using manzu:

              Agari:   or   or   or  

Using souzu:

              Agari:   or   or   or   or  

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. Without the help of computers, determining the winning tiles upon tenpai may become somewhat of a task.

Yakuman

Due to the relatively high value of this yaku, chinitsu may be involved in the formation of kazoe yakuman.

External links

Chiniisou in Japanese Wikipedia
Game designed with sou tiles only to train reading chinitsu hands.