Koi-Koi (Japanese: こいこい) is a popular card game in Japan played with Hanafuda cards which is one of ways to play Hanafuda(Japanese playing cards) with two players.
The goal of the game is to make the combination of severalcards earlier than your opponent. The phrase "koi-koi" means "come on" in Japanese which is said when the player wants to continue the hand.

The object of the game is to form special card combinations called "yaku" from cards accumulated in a point pile. Players can gain cards in their point piles by matching cards in their hands, or drawn from the draw pile, with cards on the table. Once a yaku has been made, a player can stop to cash in points, or keep going (referred to as "koi-koi", hence the name of the game) to form additional yaku for more points. The point values assigned to individual cards have no effect on the score, but they are helpful to judge their value in forming yaku.