Each week, I’ll be going through the replays of a different Tenhoui, looking at key positions and trying to understand the thought process behind their decision making. The Tenhoui I’ll be examining for this week is the newest one, yoteru, who is a semi-famous Mahjong blogger/researcher. From what I’ve seen, he plays relatively textbook, with a very well-rounded style grounded in strong fundamentals, so he is easy to learn from.

Player: yoteru, the 18th Tenhoui
Twitter: https://twitter.com/yoteru11

East Round Analysis
Replay: http://tenhou.net/0/?log=2020050703gm-00a9-0000-bcd2f71a

South 1-0

Instinct: Discard 3m. While discarding one of 36s gives us more ukeire, it’s early so we have a lot of time to draw into tenpai, and we want a strong final shape. Keep 5m over 3m so you can take in the aka-dora for a guaranteed mangan / hane tsumo potential with riichi.

yoteru: Discard 5m. There’s only one aka 5m in the game, and our hand is already riichi + 2, so we shouldn’t worry too much about unlikely value outs. Instead, we should look to increase our tenpai rate as much as possible. It’s slight, but the early 1m that kamicha dropped means that 3m is slightly more likely to be in the wall than 5m, and is thus easier to draw into. In the rare case that someone hits tenpai before us, it also means we only have to push one suji instead of two.

Takeaway: Don’t get too fixated on aka draws, and focus on winrate instead of being greedy when you already have enough value. Riichi + 2 is more than enough value, especially as dealer.

South 1-1

Instinct: Discard 6s. There are two xia in the discard pile, so if we riichi here, our wait is only 6s, which is awful. Our value outs are manzu ikki and aka 5s, and since we’re dealer we’ll take riichi + pinfu if we’re first to riichi. 6s could be dangerous later, whereas 9s looks relatively safe to both kamicha and toimen, so we sakigiri it here.

yoteru: Discard 9s. While we could sakigiri 6s, we would lose the possibility of iipeikou, which is a potential mangan out. While it is approaching mid-late game, the other players still do not seem close to tenpai yet given their discards. 9s is safer than 6s, but it is still possible that toimen/simocha will be waiting on it once they hit tenpai. The discard piles of the other players are hard to read and have a lot of unaccounted suji, so 6s isn’t that dangerous in the grand scheme of things. Altogether, the small possibility that one of those other players hits tenpai before us + they’re waiting on 6s and not 9s + we draw into manzu instead of souzu, is not worth trading away one of our potential mangan outs.

Takeaway: Always consider the tradeoffs that came with sakigiri; if it comes at the cost of potential value, it is usually not worth it. Make sure to consider the distance in speed between your hand and your opponents. Keep as many realistic mangan outs alive as possible, especially when dealer. Terminals are safer in general, but when there are a lot of unaccounted suji, middle tiles are not that much more dangerous.

South 1-2

Instinct: We have more than enough value (9600 + 600 ron minimum), and while there have already been two discarded, 4m looks like it will drop from any of the other players, so it is a strong wait. We can’t usually hope to win off the dora even if we stay dama, but terminal dora tiles are hard to use, and might drop if the other players don’t suspect anyone is in tenpai yet. We can expect something like one 4m + two 1m in the wall, 4m dropping from any player and 1m dropping from roughly one of the three players. So our winrate is very high if we stay dama. Of course, there is also the possibility for suuankou, and 3m looks relatively good in the wall, but in this case we might actually want to just keep the good wait as mangan tsumo here would basically secure 1st/2nd.

yoteru: Your instincts are right. Dama.

Takeaway: Before committing to riichi, confirm the value in your hand. Then, think about how many waits are still in the wall, and how likely it is that your wait drops from the other players if you stay dama.

South 3-0

Instinct: We’re in 1st place in South 3 with a sizable lead, and 4th place is currently dealer. We want to pass their dealership ASAP, so we should keep the usable yakuhai. Most of our tiles are all joined together, so that leaves the 1p and the lone 1m dora. 1p has some utility as it can potentially be used in an open ikki, and 1m does not help our winrate at all. Given how early in the round it is, it’s unlikely that the 1m dora gets called (roughly 10%), and even if it does, we can play around the call by holding yakuhai tiles in our hand and safely folding.

yoteru: Your instincts are right; we should sakigiri the dora here.

Takeaway: When you’re in first place and want to advance the round, if the dora is hard to use and you have a potential disarm hand, then just get rid of it ASAP. Don’t be concerned about dora calls on terminals/otakaze as you can always play around those.

Instinct: Discard 5s. Drawing around the 5s is nice, but we’re a little too far from a menzen hand and we don’t want to be forced to commit to riichi. Let’s aim for open ikki or 789 sanshoku to pass the round.

yoteru: Discard 1p. Open ikki is a bit too far to be a viable option, as it requires drawing into/calling 6p, which is a pretty big neck. Instead, we should look for 789 sanshoku as our main open disarm hand out. With the right draws (e.g. 4s + 6m), it’s possible that this hand could pivot into kuitan while holding safe tiles. Of course, this hand could also be played closed pinfu with the right draws as well (e.g. direct 7s + 3m draws).

Takeaway: Even if there’s a few terminals in your hand, a lot of hands can easily pivot into kuitan with a few good draws. Since a few good draws can change the landscape of the hand, and middle tiles let you create strong shapes from those draws, as per the general wisdom we should usually keep middle tiles instead of commiting to restrictive yaku like ikki.

Summary

• When your hand already has a good value (3 han+ with riichi is a good benchmark), there’s no need to consider improbable floating value outs like aka-dora. Instead, focus on increasing your hand’s winrate as much as possible.
• Think holistically about the potential benefits/drawbacks of sakigiri, instead of automatically commiting to the idea because it makes your hand look “safer.” Especially so if the tile you want to sakigiri is a potential value out.
• Make sure to confirm the value of your hand and consider both the likely number of your waits in the wall, and the likelihood that your waits are to drop if you stay dama or call riichi before commiting to a riichi/dama decision.
• Sakigiri the hard to use dora (terminals, otakaze) if you’re in first place in South 3 / South 4 and have a decent shot at a disarm hand.
• It’s good to keep lesser used open outs like chanta/sanshoku/ikki in mind when aiming for a disarm hand, but the general aim should be kuitan, and you should also consider if the hands can be played menzen.