Author: Flowingcloud
Please contact Flowingcloud if there are any typos, issues, or input. All feedback is welcome!
Introduction
Initially, I wanted this post to be called something related to Haitei or “Under the Sea”, but after brooding over the name, I found my initial proposal to be quite cringy, and I went with something basic and boring instead. Thus, welcome to our first Mahjong Deep Dive where we explore more beyond the fundamentals and think more about the game.
For our first post of this new series, I tried to write something that was relatively easier to understand. My main target audience when writing this post was mainly those who are beginners/intermediate and trying take their game and knowledge to the next level. Please let me know if this helped you at all!
This time, we will explore a situation that was called to attention on Twitter (aka X) which highlights the complexity of the game, even on the simplest situations. The amount of thought involved generally highlights the knowledge of a stellar player from a normal player.
Source Post: https://x.com/yuumi1102/status/1846393366986322291
The player featured is Asai Takaki-pro from SegaSammy Phoenix in a M-League game (aka-ari; 30/10 uma with 20k oka). He decides to pass the 4m chii in the actual game, but there was a question related to this situation. If you were to call the 4m, should you chii with 
or 
?
I would now like for you to pause here and jot down your thoughts and your answer, plus your reasonings for your answer. Try your best to come up with as many reasons as possible as to why you made your decision.
Deep Dive
First, how about we start with some fun facts? The pro player opinion is split pretty evenly near a perfect 50/50. In the Twitter survey, roughly two-thirds of players decided to chii with . The public opinion is slightly more divided but one-third of players still decided to chii with . Let’s start breaking down the pros and cons of each decision. Each point made with be explained later in detail.
chii + haku as yaku
Merits
-You play five blocks with relatively strong shapes. (You cut a block after the call.)
-You still have safe tiles after calling.
-You can go sanshoku doukou. (This is a meme.)
Demerits
-Haku is your only yaku.
-Your hand is now limited to 2,000 points (maybe 3,900 on red 5s draw/win).
I will start by first addressing that most pros would not think about sanshoku doukou in this situation, thus the reason why the pro opinion is split nicely in half. Meanwhile, the public opinion is probably skewed towards declaring chii with because they see the chance of sanshoku doukou. Confirming the red dora shape () is also a huge plus if you get a relatively safe mawashi path later. The main reason as to why to chii is due to the player being able to play five blocks.
Example (3p pair break after chii):
The hand becomes relatively straightforward to play after the chii. We’ll call the next available tile and cut a tile depending on the situation. If you fill the ryanmens available or make a koutsu (triplet) of haku first, then dropping a pair is the normal play. Otherwise if you make a koutsu (triplet), then cutting a ryanmen that looks easier to complete is likely the decision. Of course, if you are able to draw or chii another 4m first and complete the 23m ryanmen, there is also the choice of dropping the haku pair depending on how late that chii was declared. Also, if the hand does not progress after a few rounds and someone declares riichi, you have a relatively safe haku pair discard to fold out with.
Of course, light does not come without shadow. The hand is now limited in yaku paths and point value. Now, the hand is worth 2,000 points and speed is of importance. If someone is faster and declares an early riichi (or your hand does not progress), then the only option is to fold.
There’s also a few minor benefits that don’t really play a huge factor into the decision making. First, you get to confirm the 0m as a full shape. If you need to mawashi later, having the 0m called helps not lowering the value of the hand. If we decide to fold, not having to fold with the red five helps a lot as well.
chii + haku/tanyao flex
Merits
-You can flex tanyao and haku as the yaku.
-You have the haku pair to fold if not called early.
Demerits
-You are temporarily playing six blocks.
The merits of being able to flex both tanyao and haku are pretty clear cut for most players. Being given an extra option does not constrain the hand to going haku atozuke (and potentially furiten). Assuming a ryanmen is completed first, we can drop a pair of one of the threes ( or ), continuing to flex haku or tanyao. If we complete a koutsu (triplet) of one of the threes first, then dropping the haku pair for ryanmen-ryanmen isshanten is extremely good since our shapes are very good, plus the hand still has a remaining haku that remains as a very safe tile.
Example (Ryanmen-ryanmen isshanten after 3p pon and haku cut):
However, unlike the previous chii, there are situations where we are not able to play as efficiently as possible due to the need to maintain the tanyao-haku flex. For example if we drew a 6m, building the 066m shape is not ideal. First, we lose dora usage on 6m koutsu (triplet) completion, plus we need to break one of the pairs. Unlike above where playing three tile blocks (i.e. 233m) is much easier, there are cases where you may lose out on expanding existing blocks due to the six block constraint, or playing the block requires breaking the tanyao/haku flex.
Example (4p draw):
There are several options a player can make, but none of them are really straightforward and you always lose out on a potential draw unlike above where maintaining five blocks gives you more leeway to create strong blocks and reinforce weak blocks. A player can break the haku pair and go for tanyao here and reduce the hand to five blocks, but that has the downside of getting rid of the flex. Meanwhile, if we cut 3p and make the 34p ryanmen, we’ll still face a similar situation later if we draw anything from 1s to 5s. Generally, you want to have two head (pairs) candidates and the haku pair puts a lot of constraint since you want to play three pairs sometimes in these situations.
While you usually want to break a block early, this is a type of hand where you want to play six blocks as long as possible before slimming down the hand into five blocks. The timing to break a block depends on each person’s playstyle, but the timing is slightly awkward due to the fact that you want to maintain the haku pair.
Conclusion
Now, once again, there is no correct decision when having to make the chii with or , but understanding the pros and cons for each choice, as well as adapting to your selection based on the situation is what makes the excellent mahjong players stand out from the rest.
If you learned anything from this post at all, don’t just think about the immediate decision, but consider what the future path of your hand can be. I hope you enjoyed this first deep dive into mahjong with me and I hope to see you next time.