For the sake of simplicity, the previous theories assumed that only one player was attacking. However that is not the case in real games. Situations where one player declares riichi and another player pursues riichi or goes into kanzen shinko are not rare.
The author mentioned before that if your order of discarding during betaori is done properly, it will effectively raise the chances of having safe tiles to discard when many players declare riichi. However, there will still be times when you have no safe tiles to discard. It is at times like this, where making good judgement becomes even more important.
The aim of defending is to avoid dealing in, but when this doesn't work, avoid dealing in to big hands is the second best practice.
When facing riichi from two players and above, avoid dealing in as the value of the hand is hard to estimate. But if there are melded sets, we can estimate the value of the hand with the exposed tiles and discards. If we know that the value of the hand is small, we can ignore that player or deliberately deal in to him.
Finding safe tiles
Firstly, we need to find genbutsu that both players have, but there may not be any most of the time. The following is the usual way to discard:
1. Genbutsu of both players
2. Genbutsu of one player, suji-pai of the other
3. Suji-pai of both players
4. Suji-pai of one player, non suji-pai of the other
5. A middle tile that is a non suji-pai
However as safe tiles increase quickly(as any discard by either players become genbutsu for both players), therefore the method mentioned previously where you discard toitsu might not be useful here... Instead, appropriate use of tile reading and situation judging will be of great use here.
[First image in http://blog.jpmahjong.net/read.php/561.htm]
Two players declared riichi, what is the safest tile in your hand?
The safest tile is 1 pin. Four 2 pin and two 1 pin have already been discarded, therefore 1 pin can only be a hell wait.
If there's no safe tile in the next round, personally I will discard 4 sou. Shimocha made an ankan with 3 sou and 5 sou was discarded 3 times, the chances of 4 sou becoming mentsu is the lowest. As for 8 wan and 3 pin, they are very dangerous as the tiles near them have not been discarded. For this round of discards, if the 4 sou passes, you should be able to make it to ryukyoku.
After discarding 1 pin, you should be able to make it to ryokyoku without making any dangerous discards. Toimen is waiting on 36 wan and shimocha is waiting on 7 wan.
[Second image in http://blog.jpmahjong.net/read.php/561.htm]
The next article will talk about more complicated examples.