Pure Straight

What is Pure Straight in Japanese Mahjong

Pure Straight is a yaku in Japanese Riichi Mahjong that requires forming a complete, uninterrupted run of 1 through 9 in a single suit. Pure Straight is a yaku achieved by assembling three sequential runs in the same suit that together span from 1 through 9. While forming these sequences can be time-consuming, especially if you want to keep your hand concealed for 2 han, it can combine nicely with other concealed-hand yaku for bigger payouts. Balancing when to call tiles (and reduce the yaku to 1 han) versus maintaining concealment for a 2-han payoff is a key strategic consideration.

How to Achieve Pure Straight？

Straight Sequence from 1 to 9 in One Suit: The hand must contain three specific sequences (chows) that together cover 1-2-3, 4-5-6, and 7-8-9 in the same suit (Pin, Sou, or Man). For instance, if you have 1-2-3, 4-5-6, and 7-8-9 of Pin, you achieve Pure Straight in Pin.

Hand Structure: As with any standard Riichi hand, you still need four sets (triplets or sequences) and one pair in total. Three of those sets would be the sequences that form the pure straight, and the fourth set can be anything valid (a triplet/quad or another sequence).

Value Varies by Open/Closed:

• 2 han if your hand is fully concealed,
• 1 han if your hand is open (meaning you called at least one chow/pung).

What is the Strategy and Risk of Pure Straight?

Closed vs. Open: If you can keep your hand concealed, you’ll receive 2 han instead of 1. However, calling (chow) to quickly assemble the 1-2-3 / 4-5-6 / 7-8-9 sequences can be faster, though it reduces the yaku’s value to 1 han.

Combining with Other Yaku

• Riichi / Fully Concealed Hands: A concealed Pure Straight can be combined with Riichi (+1 han) or Fully Concealed Hands (+1 han) if you self-draw the winning tile.
• All Simples: This typically does not combine with Pure Straight, because your straight must include the 1 and 9 tiles, which invalidates All Simples (which uses only 2–8).
• Pinfu: If your Pure Straight sequences are arranged in a way that you can maintain a valueless pair and two-sided waits, you can also have Pinfu. Just keep in mind that your sequences might revolve around 1 or 9, which can complicate Pinfu’s requirements.

Suit Selection: Deciding which suit to commit to is important. If you notice you’re drawing a lot of Sou tiles early (particularly the end tiles 1, 2, 3, 7, 8, 9), you might push for Pure Straight in Souo. If you see too many key tiles (like 1 or 9) getting discarded in one suit, you may switch to another strategy.

Efficiency Considerations: Forming three specific sequences can be slower or riskier if opponents discard your needed tiles early. However, if you naturally draw a decent sequence block (e.g., 1-2-3-4-5-6 in one suit), pivoting to a Pure Straight might be efficient.

Defensive Signals: If you start calling for sequences in only one suit, especially on the 1-2-3 or 7-8-9 edges, other players may suspect Pure Straight or a flush-type hand. They might adjust their discards accordingly.