Riichi

Riichi (立直, sometimes romanized as Reach) is a declaration in Japanese Mahjong, signaling that a player is one tile away from winning (tenpai) and betting 1000 points. Making a riichi declaration imposes several restrictions on the player, but also grants certain advantages.

Requirements for Riichi

To declare riichi, a player must meet the following conditions:

• Tenpai: The player must be in tenpai, meaning they are one tile away from completing a winning hand.
• Closed Hand: The player's hand must be entirely closed, meaning no tiles can have been melded (chii, pon, or kan) except for concealed kans. An open hand cannot declare riichi.
• Sufficient Points: The player must have at least 1000 points. The 1000 points are placed on the table as a riichi stick (立直棒, riichi bou) and are collected by the player who wins the hand, or in the event of a draw, the next winner or the dealer if they win or the hand draws again.
• No Furiten: The player cannot be in furiten, meaning they cannot be waiting on a tile they have previously discarded. If the player enters furiten after declaring riichi, they must win by tsumo (drawing the winning tile).

Restrictions After Riichi

Once a player declares riichi, they are subject to the following restrictions:

• No Tile Changes: The player cannot change their hand in any way. They cannot call chii, pon, or kan, even if it would improve their hand. They can only discard the tile they draw.
• Forced Discards: The player must immediately discard any tile they draw that is not their winning tile.
• Furiten Constraint: If a riichi player enters furiten after declaring Riichi, they can only win by Tsumo.
• Cannot cancel: Riichi cannot be cancelled. If a player realizes they made an error in declaring riichi (e.g., they were not actually in tenpai), they are still bound by the declaration.

Advantages of Riichi

Declaring riichi provides several advantages:

• Yaku: Riichi itself is a yaku (a scoring combination) worth 1 han. This means the player will score at least 1 han, even if their hand would otherwise be valueless.
• Ippatsu Chance: The player has the chance to win ippatsu (一発), which is an additional yaku worth 1 han. Ippatsu is awarded if the player wins on their first draw after declaring riichi, or on the first discard after the declaration, provided no calls (chii, pon, or kan) occur in between.
• Ura Dora Chance: If the player wins, they can reveal the ura dora (裏ドラ, "under dora") indicators. These are concealed dora indicators that can significantly increase the value of the hand.
• Psychological Pressure: Declaring riichi can put pressure on other players, as they know that the player is close to winning and may play more cautiously. It also signals to the other players what tiles are considered safe, potentially giving indirect information about their hands.

Strategy

Declaring riichi is a common and important strategic decision in Japanese mahjong. Players must weigh the potential advantages and disadvantages before making the declaration. It's particularly useful when the hand is of low value, since the riichi yaku guarantees at least a minimal score. However, if the player anticipates a very high scoring hand with significant improvements possible, they may choose to keep their hand open to increase their scoring potential even further.