Uradora (Hidden Dora) - Bonus Dora for Riichi Winners

What is Uradora?

Uradora (hidden dora) is the additional dora revealed when winning with riichi. The tile underneath the regular dora indicator is flipped, and the next tile becomes uradora. A reward for successful riichi, it can lead to unexpected high scores.

Uradora is pure luck - you don’t know what you’ll get until it’s revealed. This unpredictability adds excitement to riichi and creates dramatic moments.

Basic Rules

Uradora conditions:
1. Must have called riichi
2. Must win (tsumo or ron)
3. Flip the tile under dora indicator
4. Next tile is uradora

※Ippatsu unrelated

Dora Positions

Common Usage

Example 1: Basic

"Uradora hit!"
"Ura 3 for haneman"
"No uradora..."

Example 2: Hoping

"Counting on uradora"
"Maybe mangan with ura"
"Riichi for uradora chance"

Example 3: Results

"Uradora comeback"
"Uradora explosion"
"Ura didn't hit"

Related Terms

• Riichi: Required for uradora
• Dora: Special bonus tiles
• Dora Indicator: Shows dora
• Kan Dora: Additional dora from kan
• Ippatsu: First-turn win

Common Mistakes

1. Condition confusion

   • Riichi required
   • Dama has no uradora
   • Ippatsu unrelated

2. Wrong tile

   • Under the indicator
   • Not beside it
   • Next tile is uradora

3. Timing confusion

   • Revealed after win
   • Unknown at riichi
   • Losers don’t see it

4. Counting

   • Same as dora (type × count)
   • Add to aka dora
   • 20+ theoretically possible

Probability

Uradora Hit Rate

Probability for 13-tile hand:
0 tiles: ~70%
1 tile: ~25%
2 tiles: ~4%
3+ tiles: ~1%

Expected value: ~0.35 tiles

Expected Value by Existing Dora

Riichi Strategy with Uradora

Riichi Decisions

Considering uradora:
1. Even bad shape, ura expected
   - Average 0.35 han value
   - 1000 can become mangan

2. No dora still fight
   - Ura can transform hand
   - Riichi-only → riichi+ura 3

3. High score potential
   - Mangan → haneman
   - Haneman → baiman
   - Baiman → sanbaiman

Situation-Based Riichi

Point Impact

Point Changes

Uradora point changes:
Riichi only (1 han)
→ Ura 1 (2 han): 1000→2000
→ Ura 2 (3 han): 1000→3900
→ Ura 3 (4 han): 1000→mangan

Riichi+Tanyao (2 han)
→ Ura 1 (3 han): 2000→3900
→ Ura 2 (4 han): 2000→mangan

Comeback Potential

Kan Uradora

With Kan

Kan uradora system:
1. Kan adds dora
   → Kan dora (top row)

2. Riichi win adds ura too
   → Kan uradora (bottom row)

3. Maximum combination
   Regular + ura
   + Kan dora ×4 + Kan ura ×4
   = Up to 10 types of dora

Multiple Kans

Psychological Effect

Impact on Players

What uradora brings:
1. Anticipation
   - Exciting reveal moment
   - Dream of comeback

2. Aggression
   - Motivation for riichi
   - Offensive mahjong

3. Drama
   - Unexpected outcomes
   - Emotional swings

Uradora and Mahjong Appeal

Procedure

Proper Steps

Revealing uradora:
1. Confirm win
2. Show hand
3. Declare points
4. Flip under indicator
5. Confirm uradora
6. Calculate final points

Etiquette

With Aka Dora

Dora types and calculation:
Regular dora: 5p indicator → 6p is dora
Aka dora: Red 5 (man/pin/sou)
Uradora: On riichi win

Ex: Hand has aka 5p, 6p ×2
→ Dora 3 (already 3 han)
→ If ura is 5p, +2 more
→ Total 5 han dora

Summary

Uradora is the bonus dora revealed when winning with riichi - pure luck but a major part of mahjong’s appeal. With an average 0.35 han expected, it sometimes creates dramatic comebacks. Beginners should learn “riichi win = uradora chance” as a key riichi benefit. As the saying goes, “uradora is mahjong’s flower” - this unpredictable element makes mahjong more exciting.