Twice Pure Double Sequence

What is Twice Pure Double Sequence in Japanese Mahjong

Twice Pure Double Sequence is a three-han yaku in Japanese Riichi Mahjong. It represents an advanced version of pure double sequence, requiring two separate pairs of identical sequences in a fully concealed hand. Twice Pure Double Sequence is a 3-han concealed-hand yaku in Riichi Mahjong. It builds upon the concept of Pure Double Sequence by requiring two distinct pairs of identical sequences in the same suit. While the high synergy and concealment requirements make it challenging, the reward is a robust 3-han hand that can climb even higher with Riichi, Fully Concealed Hands, and potential ura dora flips. Players must balance the difficulty of assembling two perfect double sequences against the potential for a sizable, high-scoring hand.

How to Achieve Twice Pure Double Sequence？

Two Distinct Pure Double Sequences: You must form two sets of identical sequences (chows) in the same suit. For instance, you might have (2–3–4 of Sou) x2 and (5–6–7 of Sou) x2. Each double sequence is reminiscent of Pure Double Sequence, but now you have two of them in one hand.

Fully Concealed Hands: Twice Pure Double Sequence requires the entire hand to remain Fully Concealed Hands (unopened). You cannot call chow, pung, or open kong. Concealed kongs (ankan) are allowed in principle, but realistically they can complicate or break your double-sequence structure if not handled carefully.

Standard Hand Structure: A winning Riichi Mahjong hand has four sets (triplets or sequences) plus one pair. In Twice Pure Double Sequence, four of those sets will be arranged as two sets of identical sequences (each pair of identical sequences sharing the same suit and numbers). The fifth set could be another sequence or triplet, and you still need one pair to finish the hand.

Three-Han Value: Twice Pure Double Sequence is worth 3 han by itself, making it a relatively high-value yaku. It cannot be “declared” if the hand is opened; concealment is mandatory.

What is the Strategy and Risk of Twice Pure Double Sequence?

Hand Efficiency vs. Complexity: Pursuing Twice Pure Double Sequence can be tile-intensive and slightly luck-dependent. You need to draw duplicates of two different three-tile runs (chows) all in the same suit. However, if you start seeing natural pairs of sequences forming in one suit, it might be worth shifting your strategy to aim for Twice Pure Double Sequence.

Combining with Other Yaku:

• Riichi: You can declare Riichi once in tenpai, adding +1 han.
• Fully Concealed Hands: If you self-draw the winning tile, that’s another +1 han.
• Ura Dora: Declaring Riichi gives you access to potential hidden dora flips, boosting your hand’s final value even more.
• Pinfu is sometimes possible if your pair is valueless (not honors or special wind/dragon), and your waits are all two-sided. The structure might be tricky, but it can happen.

Waiting Shapes: Twice Pure Double Sequence often leaves you with interesting multi-tile waits, since your four sequences can create overlapping shapes. If you’re aiming specifically for Twice Pure Double Sequence, keep an eye out for draws that double up your runs in the same suit—particularly if you already have an Pure Double Sequence and can replicate it with different tiles.

Risk and Reward: Committing to Twice Pure Double Sequence can sometimes slow your hand development, as you can’t meld (open) and you must hope the right tiles appear. The payoff of a 3-han base hand, plus possibly Riichi and Fully Concealed Hands, can yield a mangan (or higher) easily.