Ryuuiisou (All Green) - The Most Beautiful Yakuman

What is Ryuuiisou?

Ryuuiisou (All Green) is a yakuman made entirely of green-colored tiles - the 2, 3, 4, 6, 8 of souzu (bamboo) and the green dragon (hatsu). Also called “All Green,” it’s considered the most visually beautiful yakuman.

With only 6 tile types available, it’s restrictive but relatively achievable among yakuman since sequences are possible. Occurrence rate is about 0.0024%.

Usable Tiles

Type	Tiles	Feature
Souzu	2, 3, 4, 6, 8	Green-only numbers
Honor	Hatsu (green dragon)	Only honor tile
Total	6 types, 24 tiles	All green

Requirements

Condition	Detail	Notes
All green tiles	Only the 6 types	No others
4 groups + pair	Standard shape	Chiitoitsu (local)
Calls allowed	Chi/pon OK	Closed not required

Example Hands

With sequences

234s 234s 666s 888s HH
Complete: Green sequences + green triplets + green pair

All triplets

222s 444s 666s 888s HH
Complete: Four green triplets + green pair

Pure (no hatsu)

234s 234s 666s 22s 88s
Wait: 2s or 8s

Which Tiles Are NOT Green

Cannot use:

1s - Has red parts
5s - Has red parts
7s - Has red parts
9s - Has red parts
All other suits and honors

Building Strategy

From the deal

Green tiles	Decision	Reason
9+ tiles	Go for it	High chance
7-8 tiles	Watch	Depends on draws
6 or less	Difficult	Consider chinitsu

Approach

Cut non-green
- Other souzu too
- Keep only green
Use 234 sequence
- Only sequence possible
- Helps progress
Hatsu decision
- Use if available
- Not required

234 Sequence Advantage

Value of 234s:

Hand progress
- Easy to form groups
- Shape improves
Better waits
- Ryanmen possible
- Multi-wait options
Calling flexibility
- Can chi
- Speeds up hand

With or Without Hatsu

Type	Feature	Value
With hatsu	Easier	Standard all green
Without hatsu	Pure green	Higher aesthetic

Occurrence Rate

Statistics:

Ryuuiisou: ~0.0024%
Higher than chinroutou
Mid-range among yakuman

Compared to other color yakuman

Tsuuiisou (~0.0095%)
Chinroutou (~0.0018%)
Ryuuiisou (~0.0024%)
Chuuren Poutou (~0.0003%)

Defending Against Ryuuiisou

Warning signs

Discards
- Many red souzu (1, 5, 7, 9)
- Non-green tiles
Green tiles scarce
- Not appearing
- Someone collecting
Souzu bias
- Only certain souzu
- Unnatural cutting

Defense

Hold green tiles
- Especially 234s
- Watch hatsu too
Race to win
- Beat the yakuman
- Speed game
Attack with souzu
- Chinitsu etc.
- Compete for tiles

Local Rules

Hatsu requirement

Rule	Hatsu	Reason
General	Not required	Green is enough
Some regions	Required	Traditional
Competitive	Not required	Official rule

Special valuation

Pure all green (no hatsu):

Higher aesthetic value
Some rules: double yakuman
Purely green

Cultural Significance

Visual beauty

Unity - All green
Freshness - Bamboo green
Completion - Color harmony

Symbolism

Life force
Growth
Harmony
Peace

Souzu: Bamboo suit
Hatsu: Green dragon
Chinitsu: Similar flush
Yakuman: Maximum hands
Honitsu: Half flush

Summary

Ryuuiisou is a yakuman using only green tiles (2, 3, 4, 6, 8 souzu and hatsu) - considered the most beautiful yakuman. While limited to 6 tile types, the 234 sequence makes it relatively achievable. Beginners should remember “green tiles only” and actively pursue when dealt many green tiles. The completed all-green hand represents mahjong’s artistic beauty in full display.