 Calling koi-koi leaves the player vulnerable, as if their opponent is able to form a yaku before the caller forms another, the opponent gains double their score and the caller earns nothing.If a player has yaku totaling 7 or more points when the hand ends, that player earns twice that value.If a player hits 7 or more points "and" their opponent had called koi-koi, he gets both doubling bonuses for a total of four times their score.