Fully Outside Hand

What is Pure Outside Hand in Japanese Mahjong

Pure Outside Hand is a yaku in Japanese Riichi Mahjong that requires every set (and the pair) to include at least one terminal tile (1 or 9)—and no honor tiles are used. Below is a detailed breakdown.

How to Achieve Pure Outside Hand？

Terminal in Every Set and Pair: Each of your four sets (triplets or sequences) must contain either a 1 or a 9. The pair must also be either 1 or 9. Unlike Half Outside Hand, honor tiles (winds or dragons) are not allowed in Pure Outside Hand; only 1s and 9s in the suits (Man, Pin, Sou).

Hand Composition: A standard winning Riichi Mahjong hand has four sets plus one pair. In Pure Outside Hand, each of those five components (four sets + one pair) must include a terminal. Practically, any sequence must be 1–2–3 or 7–8–9 (because it includes a 1 or a 9). Triplets/quads would be 1-1-1 or 9-9-9 in any suit.

Value Changes if Open or Closed:

• If you keep your hand fully concealed, Pure Outside Hand is worth 3 han.
• If you open (meld) at least one set, Pure Outside Hand is typically worth 2 han.

What is the Strategy and Risk of Pure Outside Hand?

Closed vs. Open Decision: If you can afford to stay concealed, Pure Outside Hand gives you a base 3 han—which is quite valuable. However, because you need specific terminals for every set, you may find it difficult to complete all sequences/triplets quickly. You might decide to call (meld) terminal tiles to finish faster, dropping the yaku value to 2 han.

Sequences vs. Triplets: Because each sequence must be 1–2–3 or 7–8–9, if you’re missing too many of those end tiles, you’ll struggle to complete Pure Outside Hand. Triplets of 1 or 9 can also satisfy the requirement, but keep in mind triplets require three identical tiles, which can be harder to collect if opponents notice your pattern.

Potential Combinations

• Riichi: If the hand is closed, you can declare Riichi for an additional +1 han.
• Fully Concealed Hands: Self-drawing a concealed Pure Outside Hand hand grants another +1 han.
• Pinfu: Usually incompatible with Pure Outside Hand because Pinfu needs no “valued” pair and all sequences must be two-sided waits. In Pure Outside Hand, you’ll often have 1–2–3 or 7–8–9 sequences, which can still be two-sided, but your pair must be a terminal, which typically adds fu (making it not a valueless pair).

Defensive Signals: If opponents see you repeatedly calling 1s and 9s, they may guess you’re aiming for Pure Outside Hand, Pure Outside Hand, or some terminal-based strategy. Opponents might hold onto 1s/9s, or discard them in a way that’s least beneficial for you, adjusting their defensive posture.