Ryuuiisou

Ryuuiisou

Ryuuiisou (緑一色, りゅういーそう) is a yakuman where your entire hand consists solely of tiles that are visually green: the 2, 3, 4, 6, and 8 of bamboo, plus the green dragon (hatsu). All other tiles are forbidden. The name translates to “all green.”

Detailed Explanation

Requirements

To achieve ryuuiisou, all 14 tiles must be green:

• Green bamboo tiles: 2-bamboo, 3-bamboo, 4-bamboo, 6-bamboo, 8-bamboo
• Green dragon (hatsu): The green dragon tile
• No other tiles: Cannot contain any other suited tiles, honors, or bamboo 1/5/7/9

The restriction is purely visual—only tiles with green ink/coloring are allowed. Since traditional bamboo tiles have green bamboo designs and the green dragon is obviously green, these tiles meet the requirement.

Note: 1, 5, 7, and 9 of bamboo are excluded because traditional tile designs show red marks or non-green decorations on these tiles.

Strategic Considerations

Limited Tile Pool: Only six tile types qualify (2, 3, 4, 6, 8 bamboo plus green dragon), with 24 total tiles available (four each). This limited pool makes ryuuiisou challenging but more feasible than some yakuman.

Sequence Capability: Unlike tsuuiisou (all honors) which must be all triplets, ryuuiisou can form sequences: 2-3-4 bamboo, 3-4-5 bamboo (wait, 5 isn’t green), 2-3-4, 6-7-8 (wait, 7 isn’t green). Actually, sequences are limited to 2-3-4 and 6-? (but no 5 or 7). So practically, ryuuiisou tends toward triplets and the specific 2-3-4 sequence.

Green Dragon Value: A triplet of green dragons provides yakuhai (1 han) even if ryuuiisou doesn’t complete, giving incomplete hands some value.

Visual Clarity: Ryuuiisou is instantly recognizable due to its visual uniformity—all tiles appear green when revealed, creating a striking aesthetic.

Tile Design Dependency

The strict definition of “green” depends on traditional Japanese mahjong tile designs. Some modern or regional tile sets use different color schemes, which can affect what qualifies as ryuuiisou. In competitive play, the standard green tiles are universally accepted.

Usage Example

You draw several green bamboo tiles and a green dragon early in the hand. You commit to ryuuiisou, discarding all non-green tiles. You call pon on green dragons and chi on 2-3-bamboo (completing 2-3-4). Your final hand: 2-2-2 bamboo, 2-3-4 bamboo, 6-6-6 bamboo, Green-Green-Green dragon (triplets and sequences, all green tiles), plus a pair of 4-bamboo or 8-bamboo. When you win, you declare ryuuiisou (yakuman), scoring 8,000 base points (32,000 total for non-dealer) or 12,000 base points (48,000 total for dealer). Opponents marvel at the visually uniform green hand.

Related Terms

Chinitsu: Pure flush—one suit only. Ryuuiisou is similar but stricter, requiring specific green-colored tiles only.

Hatsu: Green dragon tile. Can be included in ryuuiisou hands.

Yakuman: The highest-value hand patterns. Ryuuiisou is one of the standard yakuman.