Robbing a kan

Win by taking the tile an opponent adds to an existing pon to upgrade it into a kan.

Value 1 han, open or closed
How often very rare
Mahjong hand: 2 of characters, 3 of characters, 4 of characters — 4 of circles, 5 of circles, 6 of circles — 6 of bamboo, 7 of bamboo, 8 of bamboo — 9 of circles, 9 of circles — 4 of characters, 6 of characters, winning tile: 5 of characters
An opponent adds a tile to their pon to make a kan — and that tile completes your hand.

The setup is specific: an opponent has an open pon, they draw the fourth copy of that tile, and they add it to the pon to upgrade it into a kan . If that exact tile is your winning tile, you can claim it as a ron the instant it's added. Only this added kan (shouminkan ) can be robbed; a kan built from a player's own hand can't be, except that many rules let a closed kan be robbed by a hand waiting on kokushi musou (see thirteen orphans). And because it's a ron, furiten applies as usual (see furiten).

You can't build toward chankan — staying tenpai with a live wait is the whole preparation. The lesson worth internalizing runs the other way. When you're the one upgrading a pon, that added tile is briefly claimable by every tenpai opponent: outside the kokushi exception above, the only moment in the game a tile can be won off you without being discarded. Upgrading late in the hand for a little extra fu and a fresh dora indicator, while a riichi sits on the table, is the textbook way to give one away. If you'd hesitate to discard the tile, hesitate to kan it.

Key points

Rule variations

Whether a closed kan can be robbed for kokushi musou varies by ruleset; WRC and EMA rule text governs in tournaments.

Related yaku

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