Riichi Mahjong Defense: Push or Fold, and How to Find Safe Tiles

What-to-discard (tile efficiency) is the attacking half of riichi mahjong — it gets you to tenpai. But winning also requires the other half: not dealing in. When an opponent declares riichi, the push-or-fold decision and your knowledge of safe tiles are what protect your points. As the flip side of the three attacking articles (efficiency, five-block theory, and wait selection), here is the foundation of defense.

Push or fold

Against an opponent's riichi (or an obvious tenpai), decide whether to push — keep developing your hand — or fold — discard only safe tiles. Push when you are already tenpai, or hold a good-shape, high-value hand early in the round. Fold when you are far from tenpai (2+ shanten), your hand is cheap, it is late, or the danger is high. Score and placement matter too: late with a big lead, just fold; in last place and needing points, you can push a little. It is neither all-out attack nor always folding — you choose by the situation.

Betaori — discard only safe tiles

Once you decide to fold, fold completely (betaori) — discard only safe tiles, even if it means breaking up your hand. A single deal-in to a big hand (a mangan or haneman) can wipe out several of your own wins. Pushing half-heartedly and feeding a big hand is far worse than dismantling a mediocre hand to stay safe. When you judge you can no longer win the hand, let go of it and switch to defense.

Finding safe tiles — genbutsu, suji, and the wall

In order of how safe they are: genbutsu first, then suji and the wall.

• Genbutsu (already discarded): a tile already in the riichi player's discard pond. By the furiten rule they cannot ron it, so it is 100% safe against that player. Tiles other players discard after the riichi that pass (are not ronned) also become safe — your pool of safe tiles grows every turn.
• Suji: if the reacher discarded a 4, then 1 and 7 are its 'suji'. A two-sided (ryanmen) wait — 2-3 waiting on 1-4, or 5-6 waiting on 4-7 — would be furiten on the discarded 4, so 1 and 7 are relatively safe against a ryanmen. But suji does NOT help against a kanchan, penchan, tanki, or shanpon wait, so it is only 'relatively' safe.
• Wall (no-chance): if all four copies of a number tile are visible to you, no opponent can hold a ryanmen built on it. For example, if all four 8s are visible, the 7-8 ryanmen (which waits on 6 and 9) is impossible, so 9 cannot be a ryanmen wait and is relatively safe — a tanki or shanpon wait still remains, so don't over-trust it.

Why avoiding a deal-in is worth so much

The biggest point swings in mahjong usually come from deal-ins. The points you lose by feeding a big hand are often far larger than what you gain from one of your own wins, so preventing a single deal-in is frequently worth more than scoring one extra time. This matters most in the all-last hand (oorasu) and whenever placement is on the line: defense that avoids a deal-in protects your standing directly. Weighing the value of attacking against the risk of dealing in is the heart of strong play.

The link to offense (what-to-discard), and how to practice

Defense is the mirror image of offense. The better you understand what shapes you wait on (wait selection), the better you can read an opponent's wait and spot safe tiles. TsumeDojo's what-to-discard problems train tile efficiency — your attacking base. Build the skill to reach a good-shape tenpai quickly, then at the table hunt for genbutsu, suji, and the wall against a riichi. Moving back and forth between attack and defense is what becomes a winning game.