Pinfu is a 1-han yaku that is relatively simple to complete. Its low score value is deceptive: it is an incredibly versatile hand that allows you to understand, practice, and demonstrate many advanced riichi techniques. On this page, I will attempt to explain several more complex riichi concepts using the pinfu yaku to exemplify their application.

What is pinfu?

There are three qualifications your hand must meet to score pinfu. First, your hand must be closed. Secondly, your hand must contain all sequences and a valueless pair (any number tile, or a non-yakuhai wind). Thirdly, the last tile you are waiting on must be a double-sided wait to complete a sequence. The third qualification is the most difficult for many beginners to understand, but it is also the core of pinfu, and understanding the concept will improve your overall skill as a mahjong player.

Protoruns and tile waits

The following subsection is paraphrased from Riichi: Book 1, an intermediate-level riichi strategy guide.

A protorun is one of the basic building blocks of a riichi hand. It consists of two tiles that, when combined with a third tile, completes a three-tile set. A protorun on its own is generally useless: it is "waiting" on its third tile in order to provide value to your hand. There are four types of protoruns:

Name	Example	Wait	Acceptance
side wait (ryanmen)		-	2 kinds-8 tiles
closed wait (kanchan)			1 kind-4 tiles
edge wait (penchan)			1 kind-4 tiles
pair			1 kind-2 tiles

As you can see, the side-wait protorun accepts two types of tiles: This is the two-sided wait that is required to complete pinfu. It is also the strongest protorun to have in your hand in general: As a rule, the more types of tiles that can directly improve your hand, the better off you are. Tile acceptancy is the term used to describe the amount of tiles that can improve your hand.

Improving your hand doesn't always mean getting one step closer to tenpai. You can adjust the composition of your hand in order to accept more types of tiles. For instance, you can upgrade an edge-wait run of 🀙-🀛 into a side-wait hand 🀛🀜 by drawing 🀜. This doesn't bring your hand closer to tenpai, but now instead of only 🀚, drawing both 🀚 and 🀝 complete your protorun, bringing you closer to tenpai.

=>

draw 🀜

It is harder to make these same improvements with an edge-wait protorun, however. In order to evolve a 🀠🀡 protorun into a side-wait protorun, it takes two steps: first, to accept 🀞, and then 🀝.

=> =>

draw 🀞 draw 🀝

All three of the above steps accept 🀟: but only the third accepts an additional tile: 🀜.

Value ranking of protoruns:

side wait > closed wait > edge wait

Until now, we have not discussed pairs. From a tile acceptance perspective, pairs are the weakest type of protorun. However, pairs can perform many different roles in a hand. Each hand requires one "head" (a two-tile pair) to complete. Additionally, a pair can perform as a protoset or a component of Seven Pairs.

Pairs are at their most valuable when you have two loose pairs in your hand. This is because a hand with two pairs that is in tenpai can accept two tiles to complete the hand.

When building a pinfu hand, there are many cases where you may draw into a duplicate tile in a set you already have. Keeping this tile can be advantageous for several reasons:

• You can accept up to two types of tiles (6 tiles) to transform this into 1 pair and 1 sequence.
• You can accept up to four types of tiles (10 tiles) to transform this into 1 sequence and 1 protorun.
• Of the tiles that can transform the set into a sequence-protorun, two (6 tiles) allow for the opportunity to score the Pure Doubles Sequence yaku.

If none of these opportunities come to you, you can simply discard the duplicate at a later time.

In most cases, singlets hold little value for your hand until you draw into tiles that can turn them into a protorun. However, there can still be small amounts of value gained by discarding weaker singlets in favor of better ones. This is why the first four or so discards of many Mahjong rounds will entirely consist of loose terminals and honor tiles from most players: these tiles hold no value by themselves, and a very limited number of tiles can give them value in your hand.

Scoring Rules

As previously mentioned, pinfu is a 1-han yaku. But what exactly does that mean? Below is a general scoring table to understand the value of a han in riichi:

Number of Han	Non-Dealer Win	Dealer Win
1	1000	1500
2	2000	3000
3	4000	6000
4,5	8000	12000	Mangan
6,7	12000	18000	Haneman
8,9,10	16000	24000	Baiman
11,12	24000	36000	Sanbaiman
13+	32000	48000	Yakuman

As you can see, each han exponentially multiplies the value of your hand. A 1-han hand is not very valuable at all on its own, but what makes pinfu so valuable is the amount of yaku it is compatible with.

• Riichi: 1 han. Most of the time, when you're in tenpai with a closed hand, you will make this bet.
• Ippatsu: +1 han. Awarded if the winning tile is recieved before the riichi player's next discard.
• Double Riichi: +1 han. Awarded if Riichi is called on the player's first discard.
• Tsumo: 1 han. Awarded if a closed hand in tenpai draws into a winning tile.
• Tanyao (all simples): 1 han. Awarded if a hand contains no terminal (1-9) or honor tiles.
• Iipeikou (pure double sequence): 1 han. Awarded for having two identical sequences in a hand.
• Ikkitsuukan (pure straight): 2 han. Awarded for having 123 456 789 in one suit.
• Sanshoku (mixed triple sequence): 2 han. Awarded for having an identical sequence across three different suits.
• Junchan (pure outside hand): 3 han. Awarded if every tile group and pair contains a 1, or a 9.
• Honitsu (half-flush): 3 han. Awarded if a hand is composed of honor tiles and a single suit.
• • Chinitsu (pure flush): 6 han. Awarded if a hand is composed of a single suit.
• Haitei/Houtei: 1 han. Awarded if the hand wins on the last tile draw or discard.
• Chankan (robbing a kan): 1 han. Awarded if another player calls an open kan on the last tile you need.

On its own, a riichi pinfu hand is worth 2 han. Being lucky enough to get both tsumo and ippatsu nets you 4 han, enough for a mangan. The general weakness of edge-waits encourages synergy with tanyao when building a pinfu hand. Additionally, the wide range of tiles that can form pinfu allows you to accept dora tiles quite often, especially if you're playing with the red five rule. Calling riichi grants you access to additional ura dora. With careful planning and a bit of good luck, it's possible to turn this 1-han yaku into a hand worth haneman.

Defense: How to not deal into pinfu

Of course, you're likely to not be the only player going for this yaku at the table, especially if you're playing with more experienced players. Learning not to deal in to other people's hands is as important as knowing how to build your own. When people are playing with open hands, it's easier to determine which tiles might hold value to them from their open sets: with closed yaku like pinfu, it's much harder to predict which tiles may be safe to discard.

At a beginner and intermediate level of play, the best indicator that an opponent is in tenpai with a closed hand is a riichi call. This section will discuss defending against one player in tenpai, with the awareness that what is safe against one player is not always safe against other players. In most situations, however, the opponents you must be most concerned with defending against are those actively in riichi, due to the increased value from hidden ura dora tiles, and many of the principles discussed here can be used against multiple opponents as you develop as a riichi player.

Furiten

The rule of furiten states that if you are in tenpai and a tile that you can win off of is in your discard pile, you may not win off of other players' discards. When applying this rule to defense, you can know that any tile that your opponent has previously discarded will always be a safe tile, as if it was a tile they needed to win, they would be in furiten. Additionally, any tile discarded by any other player while your opponent is in riichi is also a safe tile, as refusing to ron off of their winning tile while in riichi also puts them in furiten. When defending, these should be your first priority for discard, as they are 100% safe.

If multiple players call riichi, your pool of guaranteed furiten tiles is limited to all tile discards starting from the last riichi call.

Suji

When a numerical tile is 2-away from another tile, it is considered suji to that tile. The theory of suji is that often, players will try to call riichi on a two-sided wait (with a side-wait protorun, such as 🀛🀜), and due to the furiten rule, players can not win off of winning tiles they have previously discarded. These two insights mean that if a player discards a numerical tile, you can predict which shape they are not waiting to complete, and predict safe tiles from that insight.

For instance, if a player discards the 4 of circles, you know that they are not waiting to complete a 2-3 shape, and thus the 1 of circles is likely to be a safe discard. The opposite, however, is not necessarily true: If a player discards the 1 of circles, it is possible that they have a 5-6 shape in their hand, and so may be waiting on a 4. However, if a player discards the suji tiles on both sides of a tile (in this instance, 1 and 7), the 4 becomes a safer discard. Since the 4 of dots has two suji tiles, the 1 and 7 are both considered half-suji to the 4. Suji pairs are 1-4, 2-5, 3-6, 4-7, 5-8, and 6-9.

Kabe

Kabe is a defensive principle that relies on counting visible tiles both in your hand and on the field. By identifying which tiles have been depleted from the live wall, you know which tiles your opponent cannot have in their hand. For example, if you can see all of the three of circles, you know that your opponent can't be waiting on a 2-3 shape, which increases the likelihood of the 1 and 4 of circles being safe tiles.

Due to the fast-paced nature of mahjong, kabe is an incredibly difficult principle to put into practice.