Kakan (Added Kan) - Adding the 4th Tile to a Pon

What is Kakan?

Kakan (added kan) is a basic mahjong action where you add the 4th tile to an existing pon to form a kantsu. When you draw the 4th tile of a set you’ve already ponned, you declare “Kakan” to upgrade it.

After kakan, you draw a rinshan tile and a new kandora is revealed. Unlike minkan or ankan, kakan has unique rules and risks since it requires an existing pon.

Conditions

Condition	Details	Example
Already ponned	Have an exposed triplet	Ponned three 5m
Draw the 4th	Self-draw same tile	Draw 5m
Declare “Kakan”	Announce required	Voice it clearly
Draw rinshan	From dead wall	Not regular wall

Procedure

1. Have a ponned triplet
   ↓
2. Self-draw the 4th tile
   ↓
3. Declare "Kakan"
   ↓
4. Add to ponned tiles
   ↓
5. Draw 1 rinshan tile
   ↓
6. Discard 1 tile
   ↓
7. New kandora revealed (immediately)

Display Format

Pon: [5][5][sideways 5]
↓ Kakan
Kakan: [5][5][sideways 5 + stacked 5]

The added tile is placed on top of the pon, turned sideways.

When to Kakan

Do Kakan

Situation	Reason
Have dora	Hoping for kandora
Need points	Kandora boost
Aiming rinshan	Win on rinshan tile
Bad hand	Gambling on kandora

Don’t Kakan

Situation	Reason
Already tenpai	Prioritize winning
Chankan risk	Danger of ron
Strong opponents	Don’t give them dora
Kokushi warning	Terminal kakan especially risky

Kakan Benefits

Kandora increase
- New dora indicator
- Score up chance
Rinshan tile
- Extra draw
- Rinshan kaihou possible
Towards sankantsu
- 2-han yaku potential

Kakan Risks

Chankan risk (biggest)
- Only kakan can be chankannd
- Most significant risk
Dora for opponents too
- Everyone gets kandora
- May backfire
Information revealed
- Hand becomes readable
- Wait becomes predictable

Kakan vs Other Kans

Type	Prerequisite	Menzen	Chankan Risk
Kakan	Already ponned	Already broken	Yes (high)
Minkan	3 in hand	Breaks	No
Ankan	4 in hand	Keeps	No

Kakan’s Unique Features

Can be chankanned
- Only kakan
- Especially risky vs Kokushi
Pon is prerequisite
- Already open
- Can’t return to menzen
Display is distinct
- Stacked placement
- Easy to identify

Chankan Risk

What is Chankan

Being ronned during kakan:

You: Ponned 5m
↓
Draw 4th 5m
↓
Declare "Kakan"
↓
Opponent: "Ron!" (waiting on 5m)
→ Chankan complete

Chankan Conditions

Normal hands
- Waiting on the kakan tile
- Relatively rare
Kokushi musou
- Terminal kakan is dangerous
- 13-way wait = certain ron

Chankan Prevention

Be extra careful with terminals
Check opponents’ discards
Avoid late game kakan
Never kakan when tenpai

Strategic Timing

Early Game Kakan

Relatively safe
If dora, go for it
Watch hand development

Mid Game Kakan

For point boost
Consider opponent status
Weigh chankan risk

Late Game Kakan

Maximum risk
Don’t if tenpai
Watch for Kokushi

Chankan Examples

Chankan by Kokushi

Most dangerous case:

Opponent: Kokushi 13-way wait
You: Ponned East
↓
Draw 4th East
↓
"Kakan"
↓
Opponent: "Ron! Kokushi musou!"
→ Deal in to yakuman

Normal Chankan

Opponent: Waiting on 234m (3m tanki)
You: Ponned 3m
↓
Draw 4th 3m
↓
"Kakan"
↓
Opponent: "Ron!"
→ Chankan complete

Pon: Prerequisite action
Minkan: Open kan from discard
Ankan: Concealed kan
Chankan: Ron during kakan
Rinshan Kaihou: Win on rinshan

Common Mistakes

Confusing with minkan
- Kakan: Add to pon
- Minkan: Kan from start
Confusing with ankan
- Kakan: Already open
- Ankan: From concealed hand
Chankan specifics
- Only kakan can be chankanned
- Minkan/ankan can’t
Display method
- Stack on top
- Turn sideways

Summary

Kakan (added kan) is adding the 4th tile to an existing pon to form a kantsu. When you self-draw the 4th tile after ponning, declare “Kakan.” You’ll draw a rinshan tile and kandora increases, but kakan uniquely has chankan risk. Terminal kakans are especially dangerous against Kokushi. Avoid in late game or when tenpai. Beginners should learn “pon + add = kakan,” understand chankan risks, then kakan carefully when holding dora or needing points.