Ippatsu
Ippatsu 「一発」 is a yaku completely dependent on riichi. By definition, ippatsu requires a riichi declaration to be in effect, for an additional 1 han. Therefore, ippatsu cannot function as a stand-alone yaku.
| Type | Yaku |
|---|---|
| Kanji | 一発 |
| English | One shot |
| Value | 1 han |
| Speed | Riichi dependent |
| Difficulty | Luck |
It is awarded if the player receives a winning tile within an uninterrupted set of opponent tile draws after the riichi declaration. The earliest possible chance to win with ippatsu comes from the shimocha's discard (player to the right). The latest possible chance to win with ippatsu is with the player's next drawn tile after the riichi declaration. If someone calls a tile during this period, then this yaku is invalidated.
While ippatsu is generally considered to be a standard yaku, certain rulesets do not use it, in order to reduce variance and lower the value of a riichii. In general, when sitting down to play a game, ippatsu is counted unless otherwise specified or agreed on before the game.
Cancellation
In order for ippatsu to be counted, the hand must win before the hand in riichi discards its next tile. Furthermore, no interruption to the turn must occur. This means that tile calls will immediately end the chance for ippatsu. This includes any calls for kan except for a robbed kan (chankan). In sanma, the call for kita also denies ippatsu. If the riichi player declares kan or kita, ippatsu is still denied.
In other words: even if a hand is won before the next discard, if a call is made, ippatsu is denied. Thus, players can purposefully make tile calls in order to disrupt another player's chance for ippatsu.
Examples
- Kan is called prior to the riichi call; and the hand wins on the next draw without interruption. Therefore, ippatsu is valid.
- This hand wins on a discard before the next draw.
Ippatsu nullified
In this example, the hand wins from an opponent discard before the next tile draw. However, two tile calls were made prior to the win. So, ippatsu is invalid here.
Compatibility
| RCH | DRI | IPP | SMO | TAN | PFU | IPK | ITT | YAK | SDJ | SDO | TOI | SNA | SNK | CHA | JUN | RPK | SSG | HRO | HON | CHN | CHI | RIN | HAI | HOU | CHK | |
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Ippatsu is unique as it requires riichi to even be applicable. Thus, it is impossible for a hand to score with ippatsu alone. At the very minimum, a hand could be riichi with ippatsu.
Unlike riichi, ippatsu cannot be combined with two yaku: rinshan kaihou and houtei raoyui. Rinshan requires a kan call, which would invalidate ippatsu. As for houtei, a riichi declaration must be made with at least 4 tiles left in the live wall. That leaves the very last possible tile draw (and discard) belonging to the riichi declarer.
Note that chankan is compatible with ippatsu. When winning off chankan, the kan call is interrupted, so ippatsu is retained.
With haitei
The last possible chance for riichi comes when there are eighteen tiles left in the walls, counting the fourteen tiles in the dead wall. That leaves four tiles left for regular player draws. After the last possible riichi, if no tiles are called, every player would have exactly one tile draw left. Therefore, the last tile would go to the riichi declarer, allowing both ippatsu and haitei to be scored. Naturally, players may make tile calls to disrupt both yaku.
External links
- Ippatsu in Japanese Wikipedia