Wait Types (待ち)

9.1 Overview

The wait (待ち, machi) of a tenpai hand refers to the specific tiles that would complete the hand. Different wait types have different numbers of possible winning tiles and different strategic properties. Understanding wait types is essential for evaluating hand quality, calculating winning probability, and understanding fu scoring.

9.2 The Five Basic Wait Types

Ryanmen (両面待ち) — Two-Sided Wait

A two-sided wait occurs when your hand has a sequential pair (e.g., 4m-5m) that can be completed on either side (3m or 6m). This is the most desirable basic wait because it has up to 8 possible winning tiles (4 copies of each of 2 different tiles). Ryanmen waits also contribute no additional fu in the closed-ron scoring, making them compatible with pinfu. Because of their high acceptance and frequency, ryanmen waits are the backbone of efficient hand building.

Kanchan (嵌張待ち) — Closed/Middle Wait

A kanchan wait has a gap in a sequence (e.g., 4m-6m) waiting for the middle tile (5m). Only one tile type satisfies this wait, so maximum acceptance is 4. Kanchan waits add 2 fu to the hand score. While less efficient than ryanmen, kanchan waits are perfectly acceptable and sometimes strategically useful because the waited tile may be less expected by opponents defending against you.

Penchan (辺張待ち) — Edge Wait

A penchan wait occurs at the edge of a suit: 1-2 waiting on 3, or 8-9 waiting on 7. Like kanchan, only one tile type is needed (maximum 4 tiles). Penchan adds 2 fu. Penchan waits are generally the least desirable sequential wait because: (a) they have low acceptance, (b) they cannot be upgraded to ryanmen without restructuring, and (c) the waited tile (3 or 7) is a relatively common tile that opponents may hold or discard.

Shanpon (双碰待ち / シャンポン待ち) — Dual Pair Wait

A shanpon wait occurs when the hand has two pairs, and completing either pair into a triplet (by drawing or claiming the third copy) would complete the hand. For example, holding 5m-5m and 8s-8s as the last incomplete groups, waiting on 5m or 8s. Maximum acceptance is 4 (up to 2 copies of each of 2 different tiles). Shanpon adds 0 fu when the winning tile is drawn from the wall, but the completed triplet itself contributes fu. Shanpon waits are unique in that they can be won by pon as well as by tsumo.

Tanki (単騎待ち) — Single/Pair Wait

A tanki wait occurs when the hand has four complete mentsu and needs one more tile to form the pair (jantai). For example, having 13 tiles that form four complete groups with one tile left over—say, a lone 3z—waiting for the second 3z to complete the pair. Maximum acceptance is 3 (since you already hold one copy, at most 3 remain). Tanki adds 2 fu. Tanki waits have the lowest acceptance of any basic wait type, but they can sometimes be strategically advantageous because the waited tile may be very unexpected. An honor tanki (e.g., waiting on a wind tile that all copies appear to be available) can be a strong defensive wait.

9.3 Comparison Table

*Shanpon itself doesn't add wait fu, but the resulting triplet adds fu based on the type of tiles and open/closed status.

9.4 Complex and Multi-Sided Waits

Real hands often have waits that span multiple types or involve many tiles. Some notable complex waits include:

Nobetan (延べ単, "extended tanki"): A four-tile sequence like 4m-5m-6m-7m where the hand is in tanki waiting for tiles at either end (4m if waiting for the pair, or 7m). This produces a tanki-like wait on multiple tiles.

Sanmen-chan (三面張, "three-sided wait"): Three-sided waits such as 2m-3m-4m-5m waiting on 1m, 3m (internally), or 6m. These provide up to 11+ acceptance tiles and are extremely powerful.

Multiple wait combinations: Some tenpai hands can be interpreted in multiple ways, each giving a different wait. The player should always evaluate all possible interpretations to identify the one with the most winning tiles and best yaku/fu outcome.

9.5 Wait Quality and Win Rate — Data-Driven Analysis

Wait quality directly determines your probability of winning once in tenpai. Data from Tenhou's ranked games, compiled by the Japanese analytical community, provides concrete win-rate benchmarks by wait type:

These numbers illustrate why ryanmen waits are so strongly preferred: a good ryanmen wins roughly twice as often as a typical tanki. This win-rate difference compounds over hundreds of games into significant placement differences. As Asapin (朝倉康心), the first player to achieve Tenhou's highest rank (天鳳位), has noted in his analytical writings, the single largest efficiency improvement most intermediate players can make is to restructure their hands to arrive at tenpai with ryanmen waits rather than other wait types.

9.6 Upgrading Waits — A Practical Skill

When you reach tenpai with a poor wait, you should evaluate whether it is worth delaying (staying tenpai without riichi, or even temporarily going backward) to upgrade to a better wait. This concept, called "待ち変え" (machi-kae, "wait change"), is an intermediate-to-advanced skill.

9.7 Wait Type and Fu Interaction

The fu contribution of wait types (0 for ryanmen/shanpon, 2 for kanchan/penchan/tanki) occasionally affects scoring thresholds. For example, a hand at 3 han with 30 fu scores 4,000 (non-dealer ron), but the same hand at 3 han 40 fu scores 5,200 — a 30% increase. If changing from a ryanmen wait to a kanchan wait adds 2 fu, pushing the total from 30 to 40 fu (after rounding), the kanchan might actually score higher despite having fewer acceptance tiles. These edge cases, discussed in fu-optimization sections of Ide Yousuke's (井出洋介) scoring guides, are rarely decisive but illustrate the depth of the scoring system.