Safety tiles in the late game: suji, walls, genbutsu and honour counts

1. Four kinds of evidence, four strengths

Genbutsu are tiles the opponent has already discarded. After riichi he is furiten, so none of his own discards can ron him — completely safe against him, and only against him.

Suji rests on the assumption that the opponent has a two-sided wait. Every ryanmen is built from two tiles three apart (23 waits on 1 and 4), so if he has discarded 4 he cannot be holding 23 waiting for 1, and 1 becomes safe. Discarding 4 therefore makes both 1 and 7 suji.

A wall is a tile with all four copies visible — your hand, the discards, the calls and the dora indicator all count. It does not protect itself; it rules out the shapes that need it as a partner, which makes neighbouring tiles safer.

Honour tiles exist four times, so the remainder can be counted. With three visible, a shanpon is impossible (it needs two) and only a tanki remains; with two visible a shanpon is still possible; with none visible, tanki, shanpon and the value-tile use are all live.

2. Where each kind of evidence fails

Suji's weakness is that it only rules out two-sided waits. Kanchan, penchan, shanpon and tanki all ignore it. Early on, good shapes dominate and suji is reliable; late, the good shapes have either been won or discarded, closed waits make up more of what remains, and suji stops working.

A wall only works in one direction. With all four 3p visible, the shapes waiting on 2p are 13p kanchan, 34p ryanmen, 22 shanpon and a 2 tanki. The first two need a 3p, so they are impossible, leaving only shanpon and tanki — 2p is very safe. The shapes waiting on 4p include 56p ryanmen, which needs no 3p at all, plus 44 shanpon and a 4 tanki. Same wall, but 4p is merely safer than average.

Genbutsu runs out. Every safe tile you play is one you no longer have, and the late game often needs five to eight more turns of cover. Holding two safe tiles and needing six turns is a plan that fails on its own terms.

Honours fail on value. An unseen guest wind is already dangerous late; the round wind and your seat wind are worse, because they are value tiles, the opponent can call them for a yaku, and both tanki and shanpon become more attractive.

3. The order to check, late

Step one is to count safe tiles, not to judge one tile. Ask how many turns you can play safely, then decide whether to spend the most reliable tile now.

Step two is to look for walls. Is any tile fully visible? If so, list what its left and right sides each rule out instead of assuming everything beside a wall is safe.

Step three is suji, discounted. The later the riichi and the fewer good shapes in his discards, the less suji is worth.

Step four is honour counts: a guest wind with three visible beats one with two, which beats an unseen guest wind, which beats an unseen value wind.

Step five is whether the tile can be used against you. Safe is not harmless: a tile that gets called gives the opponent a meld and tempo, and late in the hand that cost often outweighs the safety itself.

4. Hand one: suji and structure at once

South 3, you are third, holding 123m 55p 78p 23s east east 99s, and you draw 5s. Your right-hand opponent has declared riichi with 4p, and 1p and 6s are already in his discards.

The evidence: with 4p discarded, 1p and 7p are suji, so the 7p in your hand is a suji tile; with 6s in his discards, 9s is suji too. On paper both 9s and 7p can go.

The structure: 9s is suji and a terminal, and the only shapes waiting on it are the 78s ryanmen (already ruled out by the 6s), 99 shanpon and a tanki — very low risk. 7p is suji as well, but 7p is half of your 78p ryanmen, so discarding it breaks a shape with eight tiles of acceptance, and you are still two shanten away with no right to dismantle offence.

So you discard 9s. Both are suji; one breaks your own hand and the other throws away a tile you were never going to use. Same strength of evidence, very different price.

5. Hand two: a wall protects one side

Turn 11, opponent in riichi. Three 3p are visible in the discards and calls, and you hold the fourth, so all four are accounted for. You hold a pair of 2p and a lone 4p, and must discard one.

Shapes waiting on 2p: the 13p kanchan and the 34p ryanmen both need a 3p, so both are dead. What remains is the 22 shanpon and a 2 tanki, and against riichi both need an unlikely holding.

Shapes waiting on 4p: the 35p kanchan and the 23p ryanmen are dead for the same reason, but the 56p ryanmen (waiting on 4 and 7) needs no 3p and is still live, plus 44 shanpon and a 4 tanki.

So the discard is 2p, not “the 4p next to the 3p wall”. A wall is directional evidence: before you use it, list the shapes on each side.

6. Hand three: save genbutsu for the last turn

Turn 13, opponent in riichi. Your only genbutsu is a single 9m. You also hold a west (two in his discards, one in your hand, three visible) and an unseen north.

With three west visible, a shanpon is impossible and only a tanki remains, with one copy left outside. North is completely unseen, so tanki, shanpon and a kokushi tanki are all possible; as a guest wind it carries no value, but the risk is clearly higher than west.

Play west this turn and keep 9m for the next one. The reason is not that west is safer than 9m, but that 9m is the only certain tile and belongs to the turn where you have no choices left. The value of genbutsu rises with time; spending it early is handing in your insurance in advance.