Ryuuiisou
By Kenji Tanaka · Updated
Definition
The all-green yakuman: only the 2, 3, 4, 6, and 8 of bamboo and the green dragon, the tiles printed entirely in green ink. Some rule sets require the dragon to be present; others allow a pure bamboo version.
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.”
Ryuuiisou, explained
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 use exactly one sequence shape: 2-3-4 of bamboo, the only run made entirely of green tiles (5 and 7 of bamboo are not green). Everything else must be triplets, kans, or the pair.
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.
Seeing Ryuuiisou in play
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 a yakuman: 32,000 points as non-dealer or 48,000 as dealer (8,000 base points, paid at four times or six times base). Opponents marvel at the visually uniform green hand.
Related Terms
Yakuman
役満
A yakuman is a limit hand, the ceiling of the scoring ladder: a fixed 32,000 points (48,000 from the dealer), regardless of fu or dora. They come from a short list of extreme patterns (kokushi musou, suuankou, daisangen, the wind and honor hands) rather than accumulation, though 13 counted han reaches kazoe yakuman in most rules, and some patterns score double in their hardest forms. Spotting a live yakuman path early is one of the few good reasons to abandon normal efficiency.
Hatsu
發
Hatsu is the green dragon, printed entirely in green ink, and the only dragon whose color gives it a second job: it is the anchor tile of the all-green yakuman ryuuiisou. As a value tile, a hatsu triplet scores 1 han of yakuhai from any seat in any round. With haku and chun it completes the sangenpai trio behind shousangen and daisangen.