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East Coast Pro Study session #1

09- 01-2025



Before anything

It’s been a while since my last post—research work has been keeping me busy! Things have been moving smoothly so far, but the next couple of weeks will be even more demanding since the school year has started. I didn't actually expect to not finishing this post in August, but the September came a little too quickly. Anyways, I posted it.

Both my career paths are progressing at their own pace, and I’m doing my best to keep everything on track. I also want to thank everyone who’s been reading my posts. Seeing those clicks and reads in the backend really motivates me to keep learning, improving, training, and promoting mahjong in the English-speaking community—especially among students.

Over the past few weeks, five Saikouisen pros from the East Coast gathered for our first log review under the guidance of Masa Pro. In this post, I’ll start by introducing our log review format, and then I’ll break down an interesting hand I played during that session. Let’s get started!


Study session format

Starting by introducing the format. Luke pro set up a tournament lobby on Mahjong Soul, and the rule is set to be

  • Starting Points: 1000

  • Tobi: ON (Game will stop after any player got negative)

  • Saikouisen Rule (Red dora: OFF, Head bump: ON, )

  • Imagination: This is the beginning of a south round league game.

  • The first dealer is picked randomly, and each next round will have the seating kept the same, and dealership either pass or remain.

  • The reason why the game is set to be one-round only is to keep everyone's thought fresh to avoid the situation that -- "Wait, I don't even remember why I did that... maybe just vibe?"

  • After this one-round, most likely the game will end. One person will be sharing the replay screen on discord (or whatever meeting platform that will be used), and everyone take turns talking through their thinking process. The thinking process can be anything, including the progression of hand, push/fold, etc.)



Let's look at this hand and go through it together.


As writer, I know what I was thinking at that moment, but I know it might be misleading with the hand condition actually open. However, in order to keep things easy, I post the screenshots with hands open. If you wish to think along with me, go ahead and cover their hands. Let's get started! I will just put the thought in the caption. Definitely let me know if the formatting is not ideal


Haipai, starting with two pairs, zero completed set. Four-shanten to seven pairs; five-shanten to normal hand; six-shanten to kokushi. The situation is tough, very slow and cheap hand at draw. Even if I draw a dora 3s it's hard to use unless seven pairs.
Haipai, starting with two pairs, zero completed set. Four-shanten to seven pairs; five-shanten to normal hand; six-shanten to kokushi. The situation is tough, very slow and cheap hand at draw. Even if I draw a dora 3s it's hard to use unless seven pairs.

First draw 8s, proceeded to three-shanten for seven pairs; four-shanten for normal hands. Kami's discard is quite standard, starting with terminal tiles. Out of all the tiles that are not paired up yet, the most useful one to other players is 5p, thus the most useless to us. Discarding 5p have several advantages and disadvantages. Advantages include an perfect suji trap if we ended up waiting on 2p, and faking the hand as a souzu half-flush. The fear to half-flush will drive people to discard non-souzu suits. Disadvantages includes that discarding middle tiles in such early game will draw a bunch of attention from other players. After balancing the good and bad, I decided to discard 5p.
First draw 8s, proceeded to three-shanten for seven pairs; four-shanten for normal hands. Kami's discard is quite standard, starting with terminal tiles. Out of all the tiles that are not paired up yet, the most useful one to other players is 5p, thus the most useless to us. Discarding 5p have several advantages and disadvantages. Advantages include an perfect suji trap if we ended up waiting on 2p, and faking the hand as a souzu half-flush. The fear to half-flush will drive people to discard non-souzu suits. Disadvantages includes that discarding middle tiles in such early game will draw a bunch of attention from other players. After balancing the good and bad, I decided to discard 5p.
9s draw, Kami discarded 6s in the previous round, seems a little quick at the second discard. 9s is a perfect seven pair tile. We have 2 of the 8s in our hand. We don't have an idea of if anyone has the other two copies of 8s, but we know for sure: if someone has a 9s in their hand, it will more likely to be a single tile. A single terminal tile will be amongst the ones people tend to get rid of as soon as possible, and thus easy to see if people have them or not. The fact that the 9s aren't visible in the discard pile yet, makes us feel a little better about its potential to be still in the wall. Let's keep the 9s and discard something else. Our first discard is 5p, because I wanted to discard from inside out. We have two choices in my mind: 4p or 2p. Putting your POV to other players' position, if you see an early ryanmen cut from hand, what would you think? If you see an early 5p2p cut, what would you think? For me , if I see early middle ryanmen cut, it can mean that the hand is quick and strong, and they are trading the ryanmen with hand value. However, if I see an early suji set, it usually mean that the hand has all blocks, probably 2-shanten, have some good shapes, and tossing floating tiles. I would say the threat level of a 5p4p cut will be higher than a 5p2p cut. Thus, i chose to cut 2p.
9s draw, Kami discarded 6s in the previous round, seems a little quick at the second discard. 9s is a perfect seven pair tile. We have 2 of the 8s in our hand. We don't have an idea of if anyone has the other two copies of 8s, but we know for sure: if someone has a 9s in their hand, it will more likely to be a single tile. A single terminal tile will be amongst the ones people tend to get rid of as soon as possible, and thus easy to see if people have them or not. The fact that the 9s aren't visible in the discard pile yet, makes us feel a little better about its potential to be still in the wall. Let's keep the 9s and discard something else. Our first discard is 5p, because I wanted to discard from inside out. We have two choices in my mind: 4p or 2p. Putting your POV to other players' position, if you see an early ryanmen cut from hand, what would you think? If you see an early 5p2p cut, what would you think? For me , if I see early middle ryanmen cut, it can mean that the hand is quick and strong, and they are trading the ryanmen with hand value. However, if I see an early suji set, it usually mean that the hand has all blocks, probably 2-shanten, have some good shapes, and tossing floating tiles. I would say the threat level of a 5p4p cut will be higher than a 5p2p cut. Thus, i chose to cut 2p.
Green dragon draw after one of the green dragon is out. Phew, good draw for one way closer to seven pairs tenpai. (2 shanten now). Several options: 1m, 4p, 9s, south, west, north. The winds are either not seen or just one cut, I prefer to keep them since they are good tiles for seven pairs, and potential pivoting to half-flush. The reason why winds are good for seven pairs, in my understanding, is that people will likely toss them if they don't make a yaku for them, and they are going for efficiency. Thus, the remaining tile in the wall can be more obvious. On the other hand, seven pair is a quite slow hand, and if any wind get ponned, it almost always gives the calling player the license to further chi/pon. Which will speed people up. In that case, keeping the wind in our hand also slows other people down. Let's get back to the hand: 1m, 4p, 9s, which one to pick. I chose 1m here, because 1m seems like a standard discard from a souzu half flush hand, and I want to reinforce people's thought on that I'm going for a souzu half-flush.
Green dragon draw after one of the green dragon is out. Phew, good draw for one way closer to seven pairs tenpai. (2 shanten now). Several options: 1m, 4p, 9s, south, west, north. The winds are either not seen or just one cut, I prefer to keep them since they are good tiles for seven pairs, and potential pivoting to half-flush. The reason why winds are good for seven pairs, in my understanding, is that people will likely toss them if they don't make a yaku for them, and they are going for efficiency. Thus, the remaining tile in the wall can be more obvious. On the other hand, seven pair is a quite slow hand, and if any wind get ponned, it almost always gives the calling player the license to further chi/pon. Which will speed people up. In that case, keeping the wind in our hand also slows other people down. Let's get back to the hand: 1m, 4p, 9s, which one to pick. I chose 1m here, because 1m seems like a standard discard from a souzu half flush hand, and I want to reinforce people's thought on that I'm going for a souzu half-flush.
7m just tsumogiri.
7m just tsumogiri.
I chose to 4p here after the dora draw... Though in the hindsight it should be better tossing south that is just one tile left. My hand is looking more suspicious than others', and the order of discarding will expose my hand. I should've played the hand as if everyone is looking closely at my tsumogiri/tedashi. Kristy pointed out during the review that the 4p toss here makes her certain that my hand is not souzu-half flush.
I chose to 4p here after the dora draw... Though in the hindsight it should be better tossing south that is just one tile left. My hand is looking more suspicious than others', and the order of discarding will expose my hand. I should've played the hand as if everyone is looking closely at my tsumogiri/tedashi. Kristy pointed out during the review that the 4p toss here makes her certain that my hand is not souzu-half flush.
Skipping the 8s pon, as we are still 3-shanten to normal hand after pon, and 45s are not that easily callable. Plus, only three blocks for half-flush.
Skipping the 8s pon, as we are still 3-shanten to normal hand after pon, and 45s are not that easily callable. Plus, only three blocks for half-flush.
Tsumogiri the not very useful 8m
Tsumogiri the not very useful 8m
Got a north and the hand proceeded to 1-shanten. Tossing South now. As I mentioned before, the south should have gone earlier.
Got a north and the hand proceeded to 1-shanten. Tossing South now. As I mentioned before, the south should have gone earlier.
Notice that toimen took a pon of white dragon and discarded 6m, I need to get tenpai faster! Tsumogiri 1m.
Notice that toimen took a pon of white dragon and discarded 6m, I need to get tenpai faster! Tsumogiri 1m.

Still useless draw of 8m, tsumogiri
Still useless draw of 8m, tsumogiri
Skipping the north Pon because apparently we are not North, and taking the normal hand route is 2 away, we need to get there fast! Tsumogiri the north.
Skipping the north Pon because apparently we are not North, and taking the normal hand route is 2 away, we need to get there fast! Tsumogiri the north.
Finally got the dora pair, which is the best case scenario here. Now the debate is, if you riichi, if you dama; if so, do you riichi and wait on West? or you wait on 9s? Feel free to not scroll down, pretend that you don't see other people's hand, just by looking at the discard pile. My decision will be written in the below section
Finally got the dora pair, which is the best case scenario here. Now the debate is, if you riichi, if you dama; if so, do you riichi and wait on West? or you wait on 9s? Feel free to not scroll down, pretend that you don't see other people's hand, just by looking at the discard pile. My decision will be written in the below section



My decision:


Oh even before that, I would like to mention that 'my choice' is not saying is correct, nor do all the previous choices, they are just one way of thinking about the situation.


Riichi and wait on West:

Reason on Riichi:

  • Riichi + Chiitoi + dora2 = 8000 (normal hit) ~ 4000/8000 (ippatsu + tsumo + ura2) Comparing to Chiitoi + dora2 = 6400 (normal hit) ~ 2000/4000 (tsumo)

  • Wait is good, terminal/honor both with 2 left unseen.

Two reasons on picking to wait on west rather than 9s -> (originally when I discarded it)

  1. Comparing west and 9s, people are less likely to toss 9s than honor tile that is one seen, for it deals into full flush while West only deals in to half-flush or what not.

  2. 9s seems safe for both dealer and shimo. It's kinda weird when the West is only one seen at the end of second row.


After discussion, I agreed that 9s is a better wait here.

Reasons on not throwing 9s but wait on 9s:

  1. Toimen is possibly half-flush, I can see all copies of 8s, but somehow 9s are only 1 seen. Toimen might has a pair of 9s, 9s would probably deal in/ get ponned. Instead, toimen clearly doesn't need a West.

  2. People's image of my hand is souzu half flush, so an honor tile won't easily come out either if someone is determined to fold.

  3. As mentioned before, since in my POV I can see all copies of 8s, and two copies of 9s, the odd of someone having a floating 9s is low, it's more expected to be in the wall. If someone draw it, and if they dare tossing it out, it deals in; if they decided to keep it, the only way of using the 9s is to get the last copy and pair them up, which is unlikely, and will cause their hand end up noten.

  4. Ah and the last detail I missed, is when the 9s came out from kami's hand, I can already see all copies of 8s. Even if we assume toimen is a half-flush on souzu, they will almost always pon the 9s in this situation: not ponning the 9s meaning toimen doesn't have the 9s pair. If they don't have a 9s pair, it doesn't make sense to keep a random floating 9s and toss two 2m from hand.


Some interesting discussion from Kristy Pro during discussion regarding this situation:

"But what if yicheng drew west or 9s into tenpai? i like riichiing and waiting on dora here. 3s feels too scary to throw even without the riichi, so you're looking to tsumo 3s. riichiing can pressure others to fold in order to buy time for tsumo. same idea as riichiing your suuankous since you're looking to tsumo those."

^ Thank you Kristy for the thoughts, and letting us share the thoughts.


At the end

All in all, this review session reminded me just how valuable it is to think beyond my own perspective. Playing through the hand was one thing, but breaking it down afterward with other pros really highlighted the subtle factors I might have overlooked in the moment. I’m grateful to Masa Pro and everyone (Luke Pro, Mike Pro, Kristy Pro) who joined—it’s not often we get to share ideas at this level, and I’m excited to keep learning from these sessions. I hope walking through my thought process was useful or at least fun to follow along with. If you spotted something I missed or have a different take on the wait choice, I’d love to hear it in the comments. Until next time, thanks for reading and supporting this journey of bringing mahjong study to a wider audience!




 
 
 

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