Kan (call)

Kan is the call used to declare a kong, a set of four identical tiles. Because it adds a tile beyond the normal three-tile meld, declaring kan always entitles you to draw a replacement tile from the dead wall, since the kong would otherwise leave your hand short. The call appears in most variants, though the exact bonuses differ.

There are three kinds of kan. A closed kan (ankan) is declared from four matching tiles you drew yourself; it keeps your hand closed for riichi purposes and is laid down with the outer tiles face-down. An open kan (daiminkan) claims a fourth tile from an opponent's discard when you already hold three. An added kan (shouminkan or kakan) upgrades an existing open pung by adding the fourth tile when you later draw it. Open and added kans make or keep your hand open.

In Japanese riichi, kan carries unique side effects. Each kan flips an additional dora indicator, which can boost every player's hand, so a careless kan can inflate an opponent's score. Winning on the replacement tile is rinshan kaihou, and an added kan can be 'robbed' by an opponent who needed that fourth tile to win, scoring them chankan. A closed kan during someone else's riichi is also one of the few actions allowed mid-riichi if it does not alter your wait.

For example, if you have already ponned 7s-7s-7s as an open pung and later draw the fourth 7s, you may declare an added kan, drawing a replacement from the dead wall. Beware: if another player was waiting on that 7s, they may rob your kan and win before your upgrade completes.