Riichi Mahjong Defense

[Takako Dito]

Ifwe decide that we are going to fold, then we should do so by discarding the safest tiles first, which would be tiles that we know are absolutely safe. Because of the furiten rule in riichi mahjong, a player cannot win off a tile they have already discarded, or has been discarded after riichi. This means that when defending against an opponent, we should first look to discard tiles that are in their discard pond (or have been discarded by anyone after riichi), as it is impossible for us to deal in with these tiles to that player. Tiles that are completely safe against a player because of the furiten rule are called genbutsu.

Obviously tiles which are genbutsu to one opponent may still be dangerous to other opponents. However, the furiten rule also prevents players from passing on a ron, and then winning before their next draw. Because of this, the tile that has immediately been discarded by the player to your left is always 100% safe against every player (for your current turn only), and in any given situation is the safest tile you can discard.

Identifying and discarding genbutsu is typically relatively easy. However in many situations we will find ourselves without any in our hand which would be 100% safe, and so we need to rely on other techniques to discard tiles that are probably safe. This can be done by looking for suji and blockaded tiles (kabe).

Suji is one of the key defensive principles in mahjong. Suji is a defensive technique that exploits the fact that two-sided waits are very strong in mahjong, and that most tenpai hands will end up with a two-sided wait (especially if our opponent has declared riichi).

The principle of suji is that if a player has discarded a tile, then not only is that tile safe (because it is genbutsu, as covered above), but if they have a ryanmen wait then the tile three tiles over would also be safe, because if player has that wait then they will be in furiten because of the discarded tile.

It is very important to note that while a discarded 4 means that the 1 is relatively safe through suji, a discarded 1 does not mean that a 4 is probably safe, as it may still be a 56 ryanmen wait on a 4. For a 4 to be probably safe, both 1 and 7 need to be discarded. For 1-4-7, 2-5-8 and 3-6-9, the middle tile is only likely to be safe if both of the outer tiles are genbutsu.

Suji is an incredibly powerful defensive tool in mahjong, because of the strong likelihood of a ryanmen wait, however it is not foolproof, and there are a few situations where we should be wary of relying on suji:

1) Suji of the riichi tile. People may hold double closed (ryankan) blocks like until quite late, and if they reach tenpai they will riichi and most likely discard . This leaves them with , waiting on . Ordinarily, suji would say that is relatively safe, but in this case it is their winning tile! Because the double closed block is quite common, and often creates this suji-trap wait, be wary of relying on suji from the riichi tile as it is more dangerous than suji earlier in the hand.

2) Suji with very early riichi. Suji relies on the fact that people are likely to build hands that lean towards ryanmen waiting shapes. For riichi in the first three or four discards, the hand has formed very quickly, and the likelihood of the final shape being a ryanmen is lower. Suji can still be used against these hands, however it is less beneficial compared to hands that have declared riichi later.

Larger blockades further increase the safety of tiles. For example, if we can see all four , and three of the , then the remaining fourth becomes 100% safe, as there is no possible shape that could be waiting on the last .

More often, we cannot see a complete blockade, but instead just three of a type of tile. In these situations for a player to have the ryanmen wait featuring that tile, they must have the last of that type of tile. For the example above, if we can see three tiles, then our opponent could have a wait if they have the last tile. In this case, is referred to as one chance as there is one remaining tile that can give a ryanmen wait for .

In a case where we can see three and three , becomes double one-chance as a ryanmen wait would require them to have both of the last of each tile. Double one-chance are still not as safe as no-chance or suji tiles, but have increased safety over non-suji tiles, especially early on.

Occasionally we find ourselves in the awkward situation where we have no completely safe tiles, no suji, and no kabe that we can call on. This happens quite often when one of your opponents declares an early riichi, as there will be very few discards to base our defensive plays on. In this situation there are two rules to follow:

The first rule in this instance is the most important, and the one that should be followed first. Honour tiles are typically quite safe to discard if we have no completely safe tiles, as they have lower utility and cannot form any waiting shape based around sequences rather than pairs and triplets. Terminals are also relatively safe (though less safe than honours) for the same reason.

For example, the dora tile and tiles around it are likely to be more dangerous (and the hand worth more if you do deal in) than the chart might otherwise suggest, as players are more likely to hold onto those tiles and have waits around them. A second honour tile is rank A and is quite safe early in the hand, however in the last few turns it can be highly dangerous to discard an honour tile if only one is visible to you at that point, as it is unusual late on for them to not already be discarded. If someone is obviously pursuing a honitsu hand, then honour tiles also become significantly more dangerous against them.

In a discussion with fellow players, some have asked me to share riichi mahjong tips. There is a vast amount of riichi tips published in strategy books and mahjong websites, but I know that a majority of these resources are in Japanese and are not accessible for most of you. I thought it would be a fun idea to share some of these tips, since I know how frustrating it is for those wanting to improve.

This is where the naka-suji is useful. What if the player had discarded 3m AND 9m? Then, the chances are that he is unlikely to be waiting with a 4m-5m or a 7m-8m chow. Ultimately, 6m becomes a relatively safer tile in this situation.

Hi, tenpaiman here (aka TMN or TemporaryMobileName or whatever else I happen to prefer to be called on any given day). Today I decided to do a translation of a mahjong article by totsugeki touhoku [とつげき東北], author of the famous Kagaku Suru Ma-jan series of books on digital playing and statistics-based theory of mahjong, discussing defense, betaori, and all that important stuff. As a preliminary to this article, you should read up on suji and kabe, which is discussed frequently in this article and forms the basis of most defense techniques in mahjong. You can do so here.

The translation omits some of the repetitions (and yes, he likes repeating the same points over and over. Not my fault!) and less important stuff. The original Japanese version of this article can be found here.

There are quite a few people who panic, hesitate, and end up discarding no-suji terminals or something like that. Choose your discard more carefully. Keep the following in mind: assume ryanmen (or dora) wait; definitely avoid dealing into an ippatsu; dealer is 50% more dangerous than nondealer; tile near dora is twice as dangerous. You should be looking for the following, in this order: (single suji against a riichi is about as safe as an edge tiles against that player).

Defense in Japanese mahjong means to avoid dealing into other players' hands by not discarding winning tiles. Defense is an important skill, especially when other players call riichi and/or have a high scoring hand. All else equal, a player with a lower "deal in rate" will have a higher chance of winning the game.

Defense is part of the game's learning curve. Typically, beginners may not be aware of defense, as guides often focus on general hand development and memorization of yaku. In the early stages of learning, a player may prioritize winning, since winning gives points. This is to some extent true, since you'll need to win at least one hand to finish first. However, it it not necessary to win every single hand to win a game.

Eventually, players learn the importance of minimizing deal-ins. Much less points are lost via tsumo or tenpai settlements than with deal-ins. In many instances, the points you lose matter more towards placement than the points you've gained. Still, a player has to produce hands, but they should know when to attack and when to defend.

Japanese mahjong offers players the ability to determine, deduce, and infer safe tiles. Players may show threats you may want to defend against, such as riichi declarations or particularly valuable open hands.

In general, tiles are safer when discarded earlier. After all, if an opponent isn't in tenpai yet, you can't deal in. Sakigiri is discarding potentially-dangerous tiles early, even if those tiles would be useful to your hand. This technique is best used when you don't care about winning (e.g. you have a cheap hand, or you have a large lead). You could also use the tile as part of a tile group, or fold by never dealing said tiles.

A number of techniques can be used to determine safe tiles. All of them rely on "visible tiles", which include tiles from the discard pile, the dora indicators, opponents' tile calls, and the player's own hand.

"Live" (unplayed) yakuhai can be dangerous, becoming more dangerous as the game goes on. They are particularly dangerous against a suspected honitsu hand. They can also be dangerous for an open hand without any apparent yaku.

Therefore, when a tile is safe, the other tiles that are 3 apart become safer. For instance, if a player has discarded 4-pin, the 1-pin and 7-pin become safer against that player. Neither 1 or 7 is perfectly safe, however. These intervals of 3 are called "suji intervals".

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