What is Ankou?
Ankou (Concealed Triplet) is a triplet of identical tiles made entirely from your own draws, without calling pon. Since opponents cannot see it, ankou is harder to read and scores higher fu than open triplets.
The term means “dark/hidden triplet” - invisible to opponents, making your hand harder to predict.
Ankou vs Minkou
| Aspect | Ankou (Concealed) | Minkou (Open) |
|---|---|---|
| Formation | Draw all 3 yourself | Made by calling pon |
| Visibility | Hidden in hand | Exposed on table |
| Menzen | Maintains closed hand | Breaks closed hand |
| Fu | Simples: 4fu / Terminals: 8fu | Simples: 2fu / Terminals: 4fu |
Ankou Examples
| Tile Type | Examples |
|---|---|
| Simple tiles | 222m, 555p, 666s |
| Terminal tiles | 111m, 999p, 111s |
| Honor tiles | EEE, WWW, RRR |
Important Rule
Ron completion is still ankou: If you have a pair like 55m and someone discards 5m for your winning tile, the resulting 555m is treated as ankou. Only calling pon makes it minkou.
Making Ankou
Probability
- Pair to triplet: ~11% (drawing remaining 2 tiles)
- Single to triplet: ~0.5% (drawing remaining 3 tiles)
Tips for Making Ankou
-
Value early pairs
- Especially honor and terminal pairs
- Dora pairs are priority
-
Resist calling pon
- When aiming for sanankou+
- When high value is expected
-
Read your starting hand
- Many pairs = triplet-oriented hand
- Consider chiitoitsu option too
Yaku Using Ankou
Yaku Requiring Ankou
| Yaku | Ankou Needed | Difficulty | Value |
|---|---|---|---|
| Sanankou | 3 | ★★★ | 2 han |
| Suuankou | 4 | Yakuman | Yakuman |
| Suuankou Tanki | 4 (single wait) | Double Yakuman | Double |
Compatible Yaku
- Toitoi: All melds are triplets
- Yakuhai: Honor ankou gives high fu
- Honroutou: Only terminal/honor triplets
Strategic Points
When to Aim for Ankou
-
Many pairs in starting hand
- 4+ pairs suggests toitoi-type
- Build with triplets in mind
-
Defensive play
- Ankou tiles become safe tiles
- Hand is harder to read
-
High value hands
- Sanankou is 2 han
- Fu tends to be higher
Advantages and Disadvantages
Advantages:
- Maintains closed hand (menzen)
- Higher fu (2x of minkou)
- Harder to read
- Can aim for sanankou/suuankou
Disadvantages:
- Difficult to make (low probability)
- Hand becomes heavy
- Progress is slower
Common Mistakes
-
Ron completion confusion
- Ron-completed triplet = ankou
- Pon = minkou
-
Ankan treatment
- Ankan also counts as ankou
- Included for sanankou/suuankou
-
Shanpon wait caution
- Tsumo = ankou
- Ron = one becomes minkou (for sanankou purposes)
-
Fu calculation importance
- Ankou is 2x minkou fu
- Watch the 30fu/40fu boundary
Related Terms
- Koutsu: Triplet (general term)
- Minkou: Open triplet (pon)
- Toitsu: Pair (2 identical tiles)
- Sanankou: Three concealed triplets
- Suuankou: Four concealed triplets (yakuman)
Summary
Ankou is a self-made triplet without calling, giving higher fu and keeping your hand concealed. While harder to form than calling pon, it enables high-scoring yaku like sanankou and suuankou. Beginners should value their pairs and learn when to resist the urge to call. Understanding ankou leads to more strategic, higher-scoring mahjong.