This article is about hand reading on Chi-Toitsu: 7 pairs, which covers why you should better read Chi-Toitsu, and feature of discarded tiles.
Hi all, thank you for checking this website! Modern Mahjong theory tells us importance of tile efficiency which maximize value of our hand, and hand reading is neglected. Especially against Riichi, it is almost impossible to read their hand or wait. But there is one Yaku that you should read when opponent Riichi.
It’s Chi-Toitsu: 7 pairs. Because 1. EV of Chi-toitsu tend to be high with Dora and Ura-dora, 2. Risk (deal in percentage) of tiles against Chi-Toitsu is quite different from that against ordinary hand.
Then how to read Chi-Toitsu ? Below is the discarded tiles of the hand above before Riichi.
You can see some feature.
1. 3-7 tiles including Ryanmen Taatsu are discarded from the early turns
2. 1-2,8-9 tiles are discarded later
3. No honor tiles is discarded in the early turns.
4.Riichi declaring tile is honor tile.
Additionally they tend to hold honor tile which 0 or 1 tile is discarded, and tend to discard when 2 tiles are discarded. These are the typical feature which we should suspect Chi-toitsu (or Toitoi), so we should note our opponent usually try to hide that they are aiming Chi-Toitsu.
On the other hand you can deny Chi-Toitsu if you find the player discard pair, but can’t deny Toitoi because the player may had 6 pairs.
Again, usually we can’t read opponent’s hand when he riichi-es, but should better judge if it is Chi-toitsu or not.
I hope this will be of some help to you!