What is Chankan? Robbing the Kan Special Yaku Explained for Beginners

What is Chankan?

Chankan (槍槓), also known as “Robbing the Kan,” is a special 1-han yaku in mahjong where you win by ron on the tile an opponent tries to use for added kan (shouminkan). The name comes from “piercing the kan like a spear.”

It’s an extremely rare yaku with an occurrence rate of about 0.05%. It’s nearly impossible to aim for deliberately and usually occurs by chance, but it’s memorable when it happens.

Detailed Explanation of Chankan

Conditions for Completion

To complete chankan, ALL these conditions must be met:

Condition	Details	Notes
Opponent’s added kan	Adding 4th tile to existing pon	Daiminkan doesn’t count
That tile is your wait	Your tenpai waiting tile	Even no-yaku + chankan = 1 han
Immediate ron	Declare when kan is announced	Timing is critical
Kokushi exception	Can chankan even ankan	Kokushi musou only

Which Kan Can/Can’t Be Robbed

Can be robbed:

Added kan (shouminkan) only
Example: 222 pon → adding 4th 2
         Can ron on this 2

Cannot be robbed:

Kan Type	Reason	Exception
Ankan	Not revealed from hand	Kokushi only
Daiminkan	Ronning discard	Normal ron instead
Already completed kan	Missed timing	None

Usage Examples

Real Game Situations

Example 1: Chankan Declaration

Opponent: "Kan!" (adding kan motion)
You: "Ron! Chankan!"

Example 2: Describing the Situation

"An unexpected chankan happened"
"Robbed the added kan for chankan"

Example 3: Aiming Expression

"There's a chankan possibility"
"With kokushi, can even rob ankan"

Mechanism of Chankan

How It Occurs

1. Opponent has pon (e.g., EEE)
2. Opponent draws 4th East
3. Opponent declares added kan
4. You are tenpai waiting on East
5. Immediately declare "Ron"
6. Chankan established (1 han + other yaku)

Importance of Timing

Declaration timing:

Simultaneous with kan declaration
Ideally before tile is revealed
Too late = invalid

Kan: Making a quad with 4 same tiles
Kakan: Adding 4th tile to pon
Kokushi Musou: Only yaku that can rob ankan
Rinshan Kaihou: Yaku cancelled by chankan
Ron: Winning on opponent’s tile

Common Mistakes and Points to Note

Points Beginners Often Mistake

Misunderstanding Which Kan
- Can’t chankan ankan (except kokushi)
- Daiminkan is regular ron
Timing Failure
- Declaration too late
- Kan becomes complete
Yaku Calculation
- Chankan itself is 1 han
- Can combine with other yaku
Special Rules
- Dead wall tile isn’t drawn
- Dora indicator isn’t flipped

Special Aspects of Chankan

Kokushi Exception

Normal chankan:

Only added kan eligible
Ankan cannot be robbed

For kokushi musou:

When in kokushi tenpai:
- Can chankan even ankan
- All kan types eligible
- Most special rule

Relationship with Rinshan Kaihou

Conflicting yaku:

Situation	Result	Explanation
Kan executed	Rinshan possible	Draw dead wall tile
Chankan success	Rinshan disappears	Kan doesn’t complete

Chankan Tactics

Difficult to Aim For

Chankan characteristics:

High randomness
- Can’t deliberately create
- Depends on opponent
Extremely low probability
- About 0.05%
- Maybe see once a year
Can’t prepare
- Never know when it comes
- Always need awareness

Situations to Be Aware Of

When possibility exists:

Opponent using many pons
- Added kan possibility
- Toitoi-style hands
Your wait is thin
- Hell wait etc.
- Opponent using 3 tiles
Late game development
- Adding kan for more dora
- Score adjustment

Chankan in Practice

Tiles Likely for Chankan

Higher probability tiles:

Honor tiles
- Often ponned
- Often added kan
Dora
- Actively ponned
- Want to use 4th tile
Terminal tiles
- Used in toitoi
- Added kan target

Impact of Chankan

Effect on game:

Psychological effect
- Opponent’s panic
- Wariness of adding kan
Tactical impact
- Suppresses kan
- More defensive play
Memorable
- Stays in memory
- Exciting moment

Chankan Rule Details

Scoring Calculation

Basic calculation:

Chankan (1 han) + other yaku
Example: Chankan + Tanyao = 2 han
         Chankan only = 1 han 1,000 pts

Special Treatment

Rule-wise treatment:

Item	Treatment	Reason
Tsumo/Ron	Treated as ron	Opponent’s tile
Dead wall	Not drawn	Kan incomplete
Kan dora	Doesn’t increase	Kan incomplete
Kan uradora	Doesn’t apply	Kan incomplete

Local Rules

Regional Variations

Adoption status:

Standard
- Adopted nationwide
- Official rules
Special rules
- Treatment of okurikan
- Yakuman treatment in some regions
Online mahjong
- Generally adopted
- Auto-judgment

Conclusion

Chankan (Robbing the Kan) is an extremely rare 1-han yaku for winning by ron when an opponent tries to add kan. With about 0.05% occurrence rate, it’s nearly impossible to aim for deliberately, but it leaves a strong impression when it succeeds. Beginners just need to remember “special yaku that can only ron during added kan” and “kokushi can even rob ankan.” If you encounter it in a real game, don’t miss the timing to declare “Ron.” Chankan is one of the fascinating yaku that shows the depth of mahjong.