What is Junchan?
Junchan (Pure Outside Hand) is a mahjong yaku where every meld and pair contains terminal tiles (1 or 9). Also called “Junchantaiyaochuu,” it’s the upgraded version of Chanta, but without honor tiles.
Closed it’s worth 3 han; with calls it drops to 2 han (kuisagari). Using only number tile terminals (no honors) makes it harder than Chanta, but the beautiful result is popular among players.
Conditions
| Condition | Description | Example |
|---|---|---|
| All melds include terminals | Sequences with ends, or 1/9 triplets | 123, 789, 111, 999 |
| Pair is terminal | Only 1 or 9 pairs | 11m, 99s |
| No honor tiles | Numbers only | Difference from Chanta |
Valid and Invalid Melds
Valid melds (○):
| Type | Examples | Notes |
|---|---|---|
| Edge sequences | 123, 789 (any suit) | Must include 1 or 9 |
| Terminal triplets | 111, 999 (any suit) | Only 1 or 9 triplets |
Invalid melds (×):
- 234, 345, 456, 567, 678 (no terminals)
- 222-888 (middle tile triplets)
- EEE, SSS, etc. (honor triplets)
Open vs Closed
| State | Han | Points (non-dealer) |
|---|---|---|
| Closed | 3 han | 5,200+ |
| Open | 2 han (kuisagari) | 2,600+ |
Junchan vs Chanta
| Item | Junchan | Chanta |
|---|---|---|
| Usable tiles | 1/9 only | 1/9 + honors |
| Han (closed) | 3 han | 2 han |
| Han (open) | 2 han | 1 han |
| Difficulty | High | Medium |
| Occurrence | ~0.3% | ~1% |
Junchan Features
-
High value
- 1 han more than Chanta
- Mangan-level base
-
Strict restrictions
- No honors allowed
- Terminals only
-
Beautiful yaku
- Built with number edges only
- Elegant completion
Compatible Yaku
| Yaku | Condition | Total Han |
|---|---|---|
| Sanshoku | 123 or 789 in 3 suits | 5 han (4 open) |
| Ittsuu | 123, 456, 789 | 5 han (4 open) |
| Ryanpeikou | Two identical sequence pairs | 6 han (closed only) |
Incompatible Yaku
- Tanyao: Opposite yaku
- Pinfu: Terminal pair NG
- Yakuhai: Can’t use honors
- Chiitoitsu: Special form
When to Aim for Junchan
-
Many terminal tiles in starting hand
- 7+ terminal tiles
- Multiple edge shapes
-
Upgrade from Chanta
- Can cut honors early
- Enough number tiles
-
Need high score
- Closed 3 han is significant
- Easy mangan potential
Strengths and Weaknesses
Strengths:
- High han value (3 han closed)
- Still 2 han when open
- Combines well with other yaku
- Beautiful completion
Weaknesses:
- Very difficult (~0.3% occurrence)
- Limited usable tiles
- Can’t use middle dora
- Waits are predictable
Practical Tips
Early Assessment
Signs to aim for Junchan:
- 8+ terminal tiles
- 3+ edge shapes
- No honors or few honors
Choosing between Chanta and Junchan:
- Honor pair → Chanta confirmed
- No honors → Aim for Junchan
- Can switch mid-game
Calling Decisions
Call actively when:
- 123 or 789 locks in
- Only 1 meld left
- Opponents moving fast
Stay closed when:
- Want 3 han closed
- Riichi possible
- Other yaku potential
Wait Selection
Junchan waits:
- Often penchan waits
- Kanchan also common
- Multi-waits are hard
Tips:
- Aim for ryanmen when possible
- Use stretched shapes
- Consider unusual multi-waits
Related Terms
- Chanta: Lower version with honors
- Routouhai: Terminal tiles (1/9)
- Yaochuuhai: Terminals + honors
- Chinroutou: All terminal triplets yakuman
- Ittsuu: Often combines
Summary
Junchan (Pure Outside Hand) is a beautiful 3-han yaku using only terminals (1/9). As the upgraded Chanta without honors, it’s harder but worth more. At ~0.3% occurrence, it’s rare, but worth aiming for when dealt many terminals. Beginners should remember “only 1/9, no honors” and learn to distinguish from Chanta. Even at 2 han when open, it’s valuable - adapt flexibly to the situation.