Reading discards: five steps from the river to a dangerous tile

1. Reading is elimination, not guessing

Most players treat reading as guessing the wait. The usable version is elimination: sort all 34 tile types into “cannot win on this”, “might win on this” and “probably waiting here”, then pick the tile whose cost you can accept.

The order matters because later evidence depends on earlier conclusions. The declaration tile comes first because it tells you how mature the wait is; genbutsu comes early because it needs no inference at all. Reverse the order and you end up explaining one uncertain assumption with another.

2. Step one: the declaration tile

Three things to read: where it sits, whether it was tsumogiri or tedashi, and which turn it happened.

Position: the sideways tile marks the declaring turn, and its relation to the discards either side of it shows what he still held at that moment.

Tsumogiri or tedashi: tsumogiri means he played the tile he had just drawn, so he was already tenpai or close to it before that turn, and the declaration tile was not chosen from his hand — it carries no information about which shapes he does not need. A tedashi declaration is chosen from the hand and carries much more: he was willing to throw it away on the turn he declared, so the shapes around it are shapes he does not need.

Turn number: a turn-6 riichi and a turn-13 riichi are different animals. Early declarations are mostly ryanmen, so suji is reliable. Late declarations come after the good shapes have been won or discarded, and what remains is kanchan, penchan, shanpon and tanki — none of which respect suji.

One point that gets skipped: the declaration tile is safe against the declarer himself. He discarded it, so he is furiten on it and cannot ron it. That holds for him and for nobody else.

3. Step two: the two turns before the declaration

A single discard says little; a sequence says a lot. Read what he discarded first and what came later.

Clearing the terminals of one suit and then discarding middles of another usually points at a flush: he is stripping the suit he does not need and putting everything into one. The reverse — middles first, terminals later — looks more like seven pairs, thirteen orphans, or plain efficiency.

Discarding middles of the same suit turn after turn says that suit is weak in his hand. If he is still discarding from one suit two turns before declaring, he is very unlikely to be waiting on a ryanmen in it.

The caveat: a sequence gives you a direction, not a wait. Direction can rank tiles by danger; it cannot certify any tile as safe. Treating direction as a conclusion is the most common reading error there is.

4. Step three: suji

One rule: if the opponent has discarded a tile, the tiles three away from it are suji. Discard 4p and 1p and 7p are suji; discard 5p and 2p and 8p are; discard 6p and 3p and 9p are.

Mind the direction. Discarding 3s makes 6s suji and nothing else — 9s is not suji, because the tile three away from 9s is 6s, which he has not discarded. Suji means “three apart”, not “the whole 1-4-7 group is safe”. Treating the group as one line is the classic beginner error.

The limit is just as clear: suji only rules out ryanmen. For a wait on 1p, the 23p ryanmen is killed by a 4p discard, but a 1p tanki and a 11p shanpon both remain; a 13p kanchan waits on 2p, not on 1p. So suji removes one shape, it does not make a tile safe.

A practical rule: suji from an early riichi can carry the decision; suji from a late riichi is supporting evidence only, because late waits are much more often closed shapes, and closed shapes ignore suji.

5. Step four: genbutsu and walls

Genbutsu are tiles he has discarded himself — 100% safe against him, because furiten is a rule, not a probability. No inference needed; mark them as certain.

But genbutsu is consumable. Three in hand means three more turns of cover; one means you have to decide which turn to spend it on. Playing your only safe tile on the first turn of a riichi is handing in your insurance early.

A wall is a tile with all four copies visible. It works by ruling out the shapes that need that tile as a partner, which makes neighbours safer — but only on one side. With all four 3p visible, 2p is down to shanpon and tanki, while 4p can still be a 56p ryanmen. Before using a wall, list the shapes on each side separately.

6. Step five: back to your own hand

Steps one to four produce a danger ranking. Step five asks whether the risk is worth taking, and that has to be answered with numbers.

For each candidate discard, compute the shanten you are left with and how many tiles of ukeire remain. If two tiles differ a tier in safety but are identical in efficiency, take the safe one. If the safe one costs you a shanten, compare it against what this hand is actually worth.

One check that gets skipped: after this discard, do you still have a safe tile next turn? If this is the last one, playing it hands the next turn's decision to the wall.

7. Hand one: tedashi riichi on turn 6

Your right-hand opponent declares on turn 6; the declaration tile 4p is tedashi. His river reads 9m, 1s, 4p, 2z, 6s. You are a non-dealer, you have just drawn 9p, and you hold 234m 567m 678s 45p 1p 9p North, fourteen tiles.

Step one, the declaration tile: 4p was tedashi, chosen from the hand, so on the turn he declared he did not need the shapes around 4p. Step two, the sequence: 9m and 1s earlier, terminals from two different suits, which is not a flush — more like ordinary efficiency. Step three, suji: with 4p discarded, 1p and 7p are suji.

Step four, subtract: 1p is suji, and the 23p ryanmen that would wait on it is killed by the 4p, leaving only tanki and shanpon. 9p has no suji protection — its suji partner is 6p, which he has not discarded — so 78p ryanmen, tanki and shanpon are all live. North is an unseen guest wind, with tanki and shanpon both possible.

Step five, price your hand: discarding 1p, 9p or North all leave 1-shanten with 4 kinds and 14 tiles of ukeire — identical efficiency. Discarding 4p or 5p drops you to 2-shanten: more ukeire in raw count, but a step backwards in shanten.

Conclusion: discard 1p. All three isolated tiles are equal in efficiency, so the only thing separating them is evidence, and only 1p has the ryanmen eliminated.

8. Hand two: tsumogiri riichi on turn 12

The player across declares on turn 12; the declaration tile 7m is tsumogiri. His river reads 9s, 1p, 9p, 7m, and on the two turns before declaring he played 1p and 9p by hand.

Step one: 7m was tsumogiri, so he was already tenpai before declaring and 7m is simply the tile he happened to draw — it says nothing about whether he needs m middles. Step two: two turns of clearing p terminals says p is weak for him; his hand points at m or s.

Step three, suji: with 7m discarded, 4m and 1m are suji. Step four, subtract: 9s is the first tile in his river, genbutsu, 100% safe; 4m is suji but late-game suji is discounted; North is an unseen guest wind with both tanki and shanpon live.

Step five, price the hand: the hand is 234p 567p 678m 89s 4m 9s 北. Discarding 9s keeps 1-shanten with 3 kinds and 10 tiles of ukeire (4m, 7s, North); discarding 4m gives 1-shanten with 5 kinds and 16 tiles; discarding North gives 1-shanten with 10 kinds and 35 tiles — the most efficient tile is also the most dangerous. Trading safety for efficiency here costs 6 tiles.

Conclusion: discard 9s. Turn 12, an opponent in riichi, and you are still 1-shanten: those 6 tiles buy very little, because reaching tenpai from 1-shanten usually takes two more turns and you do not have them. Late in the hand, genbutsu goes ahead of suji — not out of caution, but because the arithmetic says so.