Starting from this article, I'll begin to talk about Japanese mahjong's defence theory. I will first introduce common defence tactics in Japanese mahjong.
The goal of defending is rather simple, just don't discard the tile your opponent is waiting on. To achieve this, everyone might have thought: [As long as you know the tile your opponent is waiting on, you won't deal in.] Alright, now I'll invite everyone to guess, what is the player in the picture below waiting on?
"Reading point" is impossible!
The numerous mahjong books available all have theories related to discard reading, where they attempt to read the hand of the opponent just based on the discards. In most mahjong mangas, there are scenes where the opponent's waits are accurately read.
However, reality is cruel. A situation where you can accurately read the waiting tiles(a.k.a "reading point") of an opponent just by reading the discards is impossible. The discard reading skill mentioned in mahjong strategy books could be considered impressive with just an accuracy of 30%. Part of the outdated theories have also been proven to be wrong. (Such as ura-suji, aida yon ken etc)
If the reader hopes to learn perfect defence in the future theory discussions, like the emperors of old who tried to seek immortality, you'll only be disappointed.
The essence of defence in Japanese mahjong, identifying safe tiles
There is no immortality drug in this world, but there are ways to live longer. There are no techniques that allow you to see through the wait of your opponent, but there are many ways to avoid dealing in, and they are not difficult to learn.
The amount of games I've played in MFC are around 4800, with a deal-in rate of 12.6% in over 20000 hands. (winning rate of 25.1%) Compared to other so called high level Yellow Dragon players who have the similar winning rate as me, my deal-in rate is on an average at least 2% lower. But in my 4 years of playing MFC, I've never tried to guess the waiting tiles of my opponent. This proves that in order to defend well, you don't need any supernatural powers.
In order to defend well in Japanese mahjong, all you need to do is to find the safe tiles. Like the example in the picture above, I believe most of the readers are unable to guess the waiting tiles. This hand has a shanpon wait of 3 sou and 8 pin. But what we can be sure of is, you definitely won't deal in by discarding 56 pin, 7 wan and 6 sou.
If you don't follow highly accurate(with at least 98%) safe tile theories, but follow those unorthodox theories with only 20-30% accuracy, it will only end badly for you.
Strategies when opponent is in tenpai
Against an opponent's riichi, the strategies that you can employ, are the following:
1) Betaori: Totally giving up any chance of winning, and at the same time decreasing the chances of dealing-in to the minimum. This is the most commonly used tactic. In this series of articles, more than half the text will be covering this area.
2) Uchimawashi: While discarding tiles that have a good chance to be safe, continue to proceed to tenpai. If the tiles that you draw continue to be not useful, you can consider going into betaori. But if you want to be able to perform well here, you need to have good judgment, this can be difficult for beginners to grasp, therefore this article will only be briefly discussing this.
3) Kanzen Shinko: You'll discard any tile without hesitation, in simple terms you're ignoring your opponent's tenpai. The important thing to note is, even if the chance of winning is low, it does not mean that you shouldn't go into kanzen shinko. It's fine as long as you attack reasonably. (Translator note: The original text by the author didn't make sense. Therefore, I assumed that it's a typo error and changed it to what I think he really meant.)
Of course there are strategies to deliberately deal in, but the amount of them is too low.
The biggest problem with beginners, is that they go into kanzen shinko and ignore uchimawashi too often, and rarely go into betaori. They feel that they'll go into last place if they don't win the current hand. However in Japanese mahjong, as the losses from dealing into riichi is not small(riichi has ippatsu, chance of ura dora, menzen, and many other yaku), if you know your chances of winning is small, you should retreat and minimize your losses.
The next article will go into details on how to find safe tiles.