Defense Guide part 2: Kabe, Saki-giri, and Dama-ten

Here’s another basic Mahjong strategy known as Kabe, plus Dama-ten and Saki-giri which you can use against slightly tougher opponents.

Yo, this is UmaiKeiki again. If you are reading this, it means I actually made more of my defense guide (a surprise, I know). This is a continuation of my previous post which you should probably read first. I apologize if this turns into another novel/tl;dr/wall of text/whatever.

Kabe

While Suji represent information broadcast to everyone through discards, Kabe can often be privileged information gained from tiles in your own hand. “Kabe” translates as “wall”, and that’s exactly what they do: Kabe act as barriers that prevent shuntsu from being formed.

A Kabe is formed when all four instances of a number tile are visible. They can be in discards, in open melds, as Dora indicators, or in your hand. The more instances of the tile you have in your hand, the more of an advantage you have over opponents. For all they know, those tiles could still be available in the walls and they may try (unsuccessfully) to build shuntsu around them.

Kabe are great for identifying safe tiles during Betaori. Let’s suppose all four 3m are visible to you. That means nobody can have a shuntsu containing it (although, it could still be a waiting tile). Since there are no shuntsu containing it, then you know that 1m and 2m can not possibly complete any Ryanmen waits! The only waits on those two tiles can be Shanpon and Tanki.

Now let’s say you have a Kabe on 4m. This blocks three shuntsu: 2m3m4m, 3m4m5m, and 4m5m6m. Now it would still be possible for someone to have a 1m4m, 4m7m, or 5m8m Ryanmen wait, but it would be impossible for them to have a 2m5m or 3m6m wait. That makes 2m and 3m safe against Ryanmen.

Now consider a Kabe on 5m. This makes 3m6m and 4m7m Ryanmen waits impossible, but someone could still have 1m4m or 6m9m waits. Thus, the safe tiles are 3m and 7m.

By symmetry, we can show the following tiles are safe when we have a Kabe:

Kabe Safe tiles
2m 1m
3m 1m, 2m
4m 2m, 3m
5m 3m, 7m
6m 7m, 8m
7m 8m, 9m
8m 9m

As you can see, Kabe only really indicate safe “outside” tiles (123, 789). To get safe 456, you need to have TWO Kabe that form a “sandwich”.

If there are one or two tiles sandwiched between the Kabe, both are safe. For example, if you have 3m and 6m Kabe, then 4m and 5m are not usable for shuntsu — and can thus only be Shanpon or Tanki waits.

And if you have a 3m and 7m Kabe, then the inner tile, 5m, is safe, but the 4m and 6m are still dangerous.

Naturally, Kabe are only reliable when you can see all 4 instances of a tile. When all 4 are visible, it’s known as “No Chance”; if there are only three visible, it’s called “One Chance”. As you can imagine, One Chance Kabe aren’t nearly as safe. If you can see three 4m, for example, it’s still not safe to throw a 3m because the opponent you are defending against could have 4m5m waiting on 3m6m. However, if it’s a toss-up between discarding 3m and 3s, for example, it’s somewhat safer to discard the 3m.

Of course, the existence of two One Chance Kabe is much better: if you can see three 3m and three 4m then the 2m is mostly safe. However, it’s not nearly as safe as it would be if there were a No Chance.

Even if you don’t have the opportunity to use Kabe every time you defend, make sure you watch the discards so that your own shuntsu don’t get blocked by Kabe.

Saki-giri

When talking about defense in Mahjong, it’s only natural for discard reading to come up. You’ll definitely learn a lot about discard reading by studying Urasuji and Matagisuji. Suddenly, all the internet tough guys come out of the woodwork and yell “STOP READING SUJI, IT DOESN’T WORK.” What’s wrong? Surely it’s because nobody wants their own discards to be read?

Well, as it turns out, Suji really isn’t all that useful against tougher opponents. The problem is that the theories only work if (1) the opponent uses Ryanmen waits and (2) they make only the most efficient discards. Break either of these two conditions and Suji yields a bunch of misinformation, if anything.

Naturally, there are plenty of tricks designed to thwart Suji readers. Here’s the most basic one:

Let’s say you start the round with 7s8s8s in your hand. This is a great versatile setup which can become Shuntsu, Koutsu, Toitsu, or whatever you need later. Most people wouldn’t discard any of these tiles in early game simply because of the efficiency they contribute to the hand. However, it’s entirely possible that you’ll discard the 8s later in order to get a Ryanmen wait. Watch out! People will be looking for Matagi-suji in late game, so it’s possible they’ll see right through your plan. What would happen if you discarded the 8s in early game instead?

Matagi-suji are very unlikely to come out in early game (and note this well if you are playing some average or weak opponents) because most people won’t break apart a pair when there are useless inefficient tiles still in the hand — and even if they did, efficient shapes like ryanmen are likely to be filled by late game, right? So an early discarded 8s usually means 9s is safe — little do they know, you could have a 6s9s wait ready to trap them!

Here’s another example. Let’s say this time you have 6s7s7s9s. The most efficient move here is to discard 9s first, then 7s. Unfortunately, this announces to everyone that 5s8s is a dangerous wait. Instead, let’s pull a reverse-order discard here and get rid of 7s first, then 9s. We still wind up with a Ryanmen wait so nothing of value was lost, but now our discards suggest that 8s is safe.

Dama-ten

Here’s a simple technique which has a lot of versatility. Basically, Dama-ten means “silent tenpai”, and all you have to do is not declare Riichi when you hit Tenpai. In fact, there are plenty of situations where you should be doing this purely for attacking strategy — for example, if you can upgrade to a better wait or more Han, it’s a bad idea to lock in your hand with Riichi right away. What I want to point out, however, are its uses for defensive strategy, or perhaps “counter-defensive” strategy.

Riichi is an announcement to the whole table that you are Tenpai. It tells everyone that you are a threat and they should take immediate action to defend. If they do, you’ll be winning a whole lot less because everyone is throwing safe tiles at you. However, if there are people who attack recklessly right up to the point where you Riichi, you can use Dama-ten to prevent them from going into defensive mode. This way they’ll keep discarding dangerous tiles and you’ll have a much better chance of getting your winning tile from one of them.

Another reason to use Dama-ten is to keep your defensive options open. If someone else has declared Riichi, or if you think they are about to do so, you might want to avoid declaring Riichi yourself. Once you declare Riichi, you HAVE to discard everything you draw, including dangerous tiles. Using Dama-ten is a good way to be prepared in case you do draw a dangerous tile.

If you have a really high-value hand, Dama-ten can be important. (Depending on how competitive the game is, “high-value” could be as low as 8000 points.) You absolutely do NOT want to give away that you are shooting for a monster hand, or opponents will do anything they can to stop you!

Now for some counter-counter-defense. (It never ends.) If you decide to Dama-ten but tsumokiri everything after that, opponents might get an idea of what you are up to. (A reminder that tsumokiri means discarding the tile you just drew.) Make sure you don’t tsumokiri every turn or your cover will be blown! If you ever watch any pro games, you might see them going to great lengths to avoid tsumokiri when they have a good hand. It’s all about bluffing. Look weak when you are strong; look strong when you are weak.

Speaking of looking strong when you are weak, don’t forget the old No Ten Riichi trick. Just declare Riichi when you aren’t actually Tenpai, and watch everyone turn their hands into crap out of fear of your potential monster hand. Just be careful, though; since No Ten Riichi is a Chombo, you’ll have to make the payment if the round ends and you have to show your hand. Also of note is that many computer games won’t let you do anything that counts as a Chombo, so this won’t work as well in a game of internet mahjong. What you might try instead is declaring Riichi with a 1000 point hand instead of taking time to turn it into something bigger.

Naturally, all this is only useful against opponents that are defensive. If they aren’t defensive, then Riichi = free points.

14 thoughts on “Defense Guide part 2: Kabe, Saki-giri, and Dama-ten

  1. That’s not what Furiten Riichi is.

    Furiten Riichi is when you Riichi with a hand which is Furiten (i.e. cannot win on Ron because of a previous discard). This is allowed online. You might want to do it if you have, say, a Sanmen wait or as a bluff if you are the dealer.

  2. I’m a bit unsure about the tsumokiri thing… If you’re playing live, the people can see if you’re discarding the tile you just drew, but offline they can’t tell if you discarded a tile from your wall or the one you just drew.

    That’s a huge difference in online play, I guess it makes online play 10 times safer, or am I wrong?

    1. Tiles discarded from the hand are shown as discarded from the hand in the interface; tsumogiri are shown as just that. You can tell both. The only server I know that is not so easy to tell is MahjongLogic and that is one of the reasons why I avoid it.

      However, decisions based on your opponents tsumo-kiri/tedashi are secondary to optimal plays.

      1. Is there any way to change the in-game display on tenhou so that in-game tsumogiri will look the same as tsumogiri in replays (i.e. the tile looks gray)? Because I’m sure there is and I’m just to stupid to figure out how to change the settings. Thanks in advanc.

          1. Well, that sucks. And it’s stupid, too, because in all honesty it’s not like the information is not there, it’s just about ‘storing’ it in some way. Grab a pencil, a piece of paper and just use ‘o’s and ‘x’s to mark it and you’re done. Except I’m too lazy to do that, even though I bet that’d help at least a little bit.

  3. Thanks for the defense guide umaikeiki! Btw, do you have some criteria when you need to advance your haipai or when you decide to fold your haipai and decide to go defensive? (Maybe potential score/point of your haipai, how many shanten your haipai is, etc?)

    Do you also have some strategy to not feed your kamicha by letting him call chii or pon? Can you use defense strat just like what you write on the guide part 1 to avoid someone call chii/pon? Sometimes in tonpuusen game (east only round), the player will force open hand to get their agari and end the round fast.

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