Defense
Defense in Japanese mahjong means to avoiding dealing into other players' hands by not discarding winning tiles. Defense is an important skill, especially when other players call riichi and/or the threat of a high scoring hand. All else equal, a player with a lower "deal in rate" will have a higher chance of winning the game.
General overview
Defense is part of the game's learning curve. Typically, beginners may not be aware of defense, due to a greater focus towards 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 loss 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 know when to attack and when to defend.
Safe tiles
Defense focuses on finding anpai 「安牌」, or safe tiles. These are discarded tiles that opponents cannot win off of. Players should take into account all visible tiles, including tiles in discard piles, the dora indicators, tiles in your own hand, and any called tiles.
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.
Sakigiri
Sakigiri is the act of discarding tiles before they become dangerous. With each tile draw and discard, the game's conditions are constantly changing. Most of the time, players may possess winning tiles for other players in the hand. They must either be used for the hand, discarded in time, or simply kept in the hand.
Techniques to find safe tiles
A number of techniques can be used to determine safe tiles. All of them utilize visible tiles from the discards, dora indicator, and the player's own hand.
Furiten and genbutsu
The most important defense technique. Genbutsu involves tiles that are 100% safe due to the rules applied. Specifically, the furiten rule can be used:
- Any tile that an opponent discarded is 100% against them.
- Any tile that the player to your left has discarded this turn is 100% safe for this turn only.
- After an opponent declares riichi, any tile that is discarded and not won off of is 100% safe against that riichi player.
Honors
Honor tiles, especially those which have been discarded before, are generally safer. This is because the honor tiles cannot form sequences, meaning they are harder to wait off of.
- Honor tiles you can see all four copies of are safe against everything except kokushi musou. If kokushi isn't possible (e.g. all four copies of a different honor/terminal are also visible), then these honors are 100% safe.
- Honor tiles you can see three copies of are extremely safe. They can only be won off a tanki wait or kokushi musou. Even yakuhai are safe.
- Honor tiles you can see one or two of are relatively safe. They are safer if they have been discarded already. Guest winds are safer than yakuhai.
"Live" (unplayed) yakuhai can be dangerous, becoming more dangerous as the game goes on. They are especially dangerous against a suspected honitsu hand.
Suji
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Suji focuses on taking advantage of the furiten rule, and its application to the "mahjong intervals". Most two-sided or better waits will wait on tiles in the same suji, e.g. a {23} wait wins off either 1 or 4. Therefore, if a player has discarded 4-pin, the 1-pin and 7-pin become safer against that player. Neither is perfectly safe, however.
Some suji are safer than others:
- Suji terminals (1 and 9) are the safest, as they can only be targeted by a tanki or shanpon.
- Suji 2 and 8, as well as full suji of 4/5/6, are the next safest. They can be targeted by a tanki, shanpon, or kanchan.
- Suji 3 and 7 are the most dangerous, though still reasonably safe. They can be targeted by a tanki, shanpon, kanchan, or penchan.
Note that 4, 5, and 6 require two suji to be safe, e.g. 4 requires both 1-4 and 4-7. A "half suji" is not much safer than a reguar tile. For instance, if a player has discarded 7-pin, 4-pin is not safe, because the 1-4 suji is not cleared. In order for 4 to be considered a full suji, both 1-pin and 7-pin have to be safe.
Using suji on the riichi declaration tile is more dangerous than normal. This is because of the ryankan shape (e.g. 135, 246, or 357). Ryankans are often kept as they can improve tile efficiency. But if the hand reaches tenpai with a ryankan intact, then it must discard one of the tiles. In this case, a player can discard the 5 and wait on the suji tile 2.
In addition, opponents may intentionally take advantage of this strategy by setting up suji traps, like discarding a 6 and waiting on the 9. Players may also declare riichi on a one-sided wait or a shanpon wait, where suji would be useless. Relying only in suji to defend will result in many play-ins. Therefore, suji should be used when genbutsu tiles have ran out, or in Uchi-mawashi.
Kabe
Kabe is a tactic similar to suji. If all four copies of a tile are visible, then it is impossible to have a ryanmen wait on certain tiles nearby.
For example, if you can see all four copies of 3-pin, then 1-pin and 2-pin cannot possibly be part of a ryanmen wait. This is because no opponent can possibly have a 23 or 34 shape, because no opponent can have a 3 in the first place. Tiles inside a kabe, such as 4-pin or 5-pin in this case, are not much safer, similar to how half suji are not much safer.
Like suji, other waits are still possible. Kabe is comparable to suji (though kabe is safer), and should be used in a similar fashion.
The ways of defense and offense
Betaori
Betaori is pure defense - it focuses on discarding nothing but safe tiles. In this state, a player has completely abandoned all hope of developing a winning hand, only trying to minimize the chance of dealing in. At times, even a player achieving a tenpai hand may need to completely break the tenpai for avoidance. The essence of betaori is to always discard the safest tile first. Suji tiles or even hell wait only honors shouldn't be discarded before any genbutsu tiles.
Kanzen shinko
Kanzen shinko is the way of complete offense. A player basically ignores the opposing tenpai and proceeds to attack normally. It can be used with a very strong hand, a situation where a win is required, or in any case where the hand contains very few safe tiles. In the last case, one can switch to betaori if tiles in the hand become safe.
Mawashi uchi
Mawashi uchi is a half-way style. A player will aim to discard relatively safe tiles while still aiming for tenpai. Discardable tiles include honors, suji tiles and no-chance kabe tiles. From this state a player may fall back to betaori upon drawing dangerous tiles, or attack when reaching tenpai. This style is not recommended for beginners, and even for experienced players, it should be rarely used. It is appropriate to use when in a good shape iishanten for a strong hand.
External links
- Basic Defense Techniques in Mahjong
- UmaiKeiki’s defense guide — Betaori and Suji