Naki

Chii	チー	Sequences
Pon	ポン	Three-of-a-kind
Kan	カン	Four-of-a-kind

Naki (鳴き) are legal claims on discarded tiles. This allows players another source of tiles for hand completion, other than the regular wall. Upon claiming a discard, the player's hand is then considered to be open. As a result, the player loses the option to call riichi, and the hand is not eligible for the yaku, mentsumo. In addition, certain yaku decreases in value by 1-han, when opened. In spite of these, the benefits of opening a hand stems on increasing the speed of hand development, convenience, or the irrelevance of losing hand value by opening. Especially with hands valued of mangan or greater, opening the hand may be a better option than keeping it closed.

Mentsu and overview

Main article: Mentsu

As a general rule, tile calls apply to the tile immediately discarded. Naturally, players are not required to claim discarded tile; but they may do so under the condition of possessing 2 out of 3 tiles for a meld in the hand. Every discarded tile not claimed by discard remain in the discard piles, until the end of the hand.

In addition, kuikae is an additional rule to tile calls. Players may have melds within the hand; and a discarded tile may allow a tile claim. If a player wishe to create an open meld using parts of an existing meld, then a player is not allowed to discard the remainder of the meld, until one full turn later.

Tile calls

For each immediate discard, players have the option to make claims on discarded tiles based on the following conditions:

• For all claims, a player must have 2 out of the 3 tiles in the hand necessary to form a complete meld.
• Discard claims must be made immediately after discard, and before the next player's turn. Otherwise, a discarded tile remains in the discard pile and may not be claimed.
• Players reveal their two tiles and append the claimed tile. Then these three revealed tiles are placed to the right corner of the player's area.
• The claimed tile must be arranged sideways to indicate the claim. In addition, the claimed tile must be arranged on the left, middle, or right to indicate the source of the claim.
• If the discarded tile completes a hand, then any player may call ron.

Chii

Chii is applied for opening sequential melds, to form minjun. To claim and complete sequences, the player to the right of the discarder may claim the tile and call chii. This means, any player calling chii may only claim tiles from the player to the left.

Pon

Unlike "chii", the call for pon may be called from any player on the board. Toitsu, or pairs, may be upgraded to minkou, or open triplets.

Kan

Main article: Kan

Kan may work like pon, except this call has some added procedures and additional situations.