Half flush

What is Half Flush in Japanese Mahjong

Half Flush is a yaku in Japanese Riichi Mahjong where your hand consists entirely of tiles from one suit (Pin, Sou, or Man) plus any number of honor tiles (winds or dragons). Half Flush restricts your hand to one suit plus any honor tiles, yielding 4 han if fully concealed or 3 han if opened. It strikes a balance between flexibility (you can use honors) and higher-scoring potential (especially when combined with Yakuhai or dora) compared to other flush-oriented hands like Full Flush. However, revealing your intention to pursue a half flush often prompts defensive play from opponents, making tile collection more challenging.

How to Achieve Half Flush？

Single Suit + Honor Tiles Only: You may use tiles from exactly one of the three suits (Pin, Sou, or Man). You can include any number of honor tiles (winds or dragons). No tiles from the other two suits are allowed.

Standard Hand Structure: A valid Riichi Mahjong hand requires four sets (sequences, triplets, or quads) and one pair. In Half Flush, each of these sets—and the pair—must be drawn from your chosen suit and/or honor tiles.

Value Varies by Open/Closed:

• If your Half Flush hand is fully concealed, it scores 4 han.
• If you open the hand (by calling chow/pung on discards), it typically scores 3 han.

Comparison with Other Flush Hands

Pure Flush: Uses only one suit, with no honor tiles. Typically more difficult to complete but yields higher value (6 han concealed, 5 han open under common rules).

All Simples: Incompatible with Half Flush if you use honor tiles, since All Simples excludes 1, 9, and honors. Even if you tried a single suit from 2–8, adding any honor tile breaks All Simples.

What is the Strategy and Risk of Half Flush?

Open vs. Closed: Declaring Half Flush while closed offers a larger reward (3 han). If you need speed or suspect your chosen suit tiles/honors will be difficult to draw, you might choose to open (meld) for 2 han, potentially completing the hand faster.

Synergy with Yakuhai: Because you can incorporate honor tiles, triplets of your seat wind, the round wind, or any dragon will each add +1 han. Combining multiple Yakuhai sets with a Half Flush can yield a high-scoring hand, especially if you remain concealed.

Dora and Bonus Tiles: If you pick up dora tiles that match your chosen suit (or have a dora honor tile), the hand’s points can skyrocket. Conversely, avoid dora from the other suits—those would be unplayable in a Half Flush strategy.

Opponent Awareness: If you aggressively discard tiles from the other suits and keep calling (pung) or (chow) in one suit plus honors, opponents will likely realize you’re aiming for Half Flush (or possibly Full Flush). They may adjust their discards to reduce the chance of feeding you valuable tiles.