One set of identical sequences 一盃口 · iipeikou
Two identical sequences — same numbers, same suit — in a closed hand.
| Value | 1 han — closed hands only |
|---|---|
| How often | common |
You rarely plan for iipeikou from the deal. It tends to appear on its own: you hold a finished sequence like 3-4-5 of a suit, draw a second 4 of the same suit, and a duplicate sequence is suddenly two tiles away. That is the moment to notice it. If the doubled tiles also work as a pair or as part of a different sequence, stay flexible for a few turns and let the draws decide which shape you keep.
Because it needs a closed hand, iipeikou lives alongside riichi and pinfu, and the three stack comfortably. Two identical sequences are still sequences, so a pinfu-shaped hand often carries iipeikou at no extra cost. The one pairing it refuses is seven pairs: a block like 3-3-4-4-5-5 can be read as two sequences or as three pairs, but never both at once, and the hand is scored on a single reading.
The classic mistake is calling. One chii チー or pon ポン removes iipeikou along with everything else that depends on a closed hand. The quieter mistake is chasing it: at 1 han, it is rarely worth trading a good wait for.
Key points
- Closed hand only
- Upgrades to ryanpeikou (3 han) if you build two such pairs of sequences
- Does not stack with chiitoitsu — the same tiles cannot be read both ways
Related yaku
- Two sets of identical sequences 二盃口 — Two separate pairs of identical sequences in a closed hand.
- Seven pairs 七対子 — Seven different pairs. One of the standard exceptions to the four-sets-plus-a-pair pattern, alongside kokushi musou.
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