Hanafuda (Koi-Koi)

How to play Hanafuda (Koi-Koi)

Hanafuda — literally "flower cards" — is a traditional Japanese playing-card family dating back centuries, and Koi-Koi is by far its most popular game. Instead of numbers and suits, a hanafuda deck has 48 small cards arranged into twelve months, each month illustrated with a different flower or plant. Two players take turns matching cards by month, sweeping pairs into their own capture pile, and combining those captures into scoring sets called yaku. The twist that gives the game its name comes when you complete a yaku: you may STOP and bank your points, or shout "Koi-Koi!" ("come on!") to keep playing for a bigger score — at the risk that your opponent scores first. This version pits you against an offline computer opponent over a series of rounds, with three difficulty levels and ranking points for winning the game.

The goal

Score more points than the computer across the match. Each round you capture cards and form yaku; when you STOP, the yaku points are added to your running total (multiplied if anyone has called koi-koi). The match runs for up to twelve rounds, but it ends the moment either player reaches the target score. Whoever has the higher cumulative score wins the game — and beating the computer earns ranking points.

The deck: 48 cards, twelve months

The deck has 48 cards: twelve months of four cards each. Every card belongs to one of four types, and the number of each type is fixed. In this app each card shows its month number, an original stylised motif for that month, and a small badge for its type — the artwork is our own, not a copy of any published hanafuda deck. The four types are:

• Brights (Hikari) — 5 cards, the most valuable. They live in months 1 (crane), 3 (curtain), 8 (moon), 11 (the "rain-man") and 12 (phoenix).
• Animals / Seeds (Tane) — 9 cards, one in most months, including the boar (July), the deer (October), the butterfly (June) and the September sake cup.
• Ribbons (Tanzaku) — 10 cards. Three carry red "poetry" ribbons (January, February, March), three carry blue ribbons (June, September, October), and the rest are plain red ribbons.
• Plains (Kasu) — 24 cards, the ordinary flower cards. They are worth the least on their own but count toward the Kasu yaku when you gather ten or more.

The deal

At the start of each round the deck is shuffled and dealt: eight cards to your hand, eight cards to your opponent, and eight cards face-up onto the FIELD in the middle. The remaining 24 cards form a face-down DRAW pile. You can see your own hand and the field, and both players' capture piles, but never your opponent's hand — that hidden information is exactly why Koi-Koi is a game against the computer rather than a same-screen game.

Taking a turn

• Play a card from your hand. If it shares its MONTH with one or more cards on the field, you capture: the played card and the matching field card both go into your capture pile.
• If no field card shares the month, your card is simply placed on the field, where it may be captured later. When two field cards share the month you play, you choose which one to take; when three share it, you capture all four of that month at once.
• After playing, flip the top card of the draw pile. It captures a matching field card the same way, or is placed on the field if nothing matches — so each turn you play two cards in total.
• If your captured cards now complete a new yaku, the round pauses and you decide: STOP to bank your points and end the round, or KOI-KOI to play on. If you have not made a new yaku, your turn ends and the computer plays.

The yaku (scoring sets) in this game

A yaku is a scoring combination of captured cards. This game implements the core Koi-Koi set below. The bright yaku are mutually exclusive (only your single best one counts); every other yaku stacks, so a strong round can combine several. Points are shown next to each set:

• Brights: Five Brights / Gokō = 10; Four Brights without the rain-man / Shikō = 8; Four Brights including the rain-man / Ame-Shikō = 7; Three Brights without the rain-man / Sankō = 5. Important: the November "rain-man" bright is excluded from Sankō — three brights that include it score nothing.
• Animals: Boar-Deer-Butterfly / Ino-Shika-Chō = 5 (the July boar, October deer and June butterfly together). Separately, any five animal cards = Tane 1 point, plus 1 more for each extra animal beyond five.
• Ribbons: the three red poetry ribbons / Aka-tan = 5; the three blue ribbons / Ao-tan = 5. Separately, any five ribbon cards = Tan 1 point, plus 1 for each extra beyond five.
• Plains: ten plain cards / Kasu = 1 point, plus 1 for each extra beyond ten. (The sake cup counts as an animal for Tane, not as a plain.)
• Viewing sets, using the September sake cup: Flower Viewing / Hanami-zake = the cherry-curtain bright (March) with the sake cup = 5; Moon Viewing / Tsukimi-zake = the moon bright (August) with the sake cup = 5.

Stop or Koi-Koi?

This is the heart of the game. When you complete a yaku you may STOP and immediately win the round, banking your points. Or you may declare KOI-KOI and carry on, hoping to add more yaku for a bigger pay-out. But koi-koi is a gamble: while you keep playing, your opponent can complete their own yaku and STOP, taking the round from you. Every koi-koi call in a round raises a multiplier — the eventual winner's score is doubled for each koi-koi that was declared. So calling koi-koi and then winning is very lucrative, but calling koi-koi and then losing hands your opponent a doubled score. Once you have called koi-koi you can only stop again after forming a strictly bigger yaku set.

Scoring and the match

When a player stops, their round score equals the sum of their yaku points multiplied by two raised to the number of koi-koi calls made that round (by either player). That amount is added to their match total. If both hands run out before anyone stops, the round is a scoreless draw and the deal passes. The match continues, rotating who deals first, until a player reaches the target score or twelve rounds have been played; the higher total then wins. (We use the koi-koi multiplier only; the optional "seven-or-more points doubles" house rule is not applied.)

Playing the computer (ranked)

Choose one of three difficulty levels before you start. Easy captures loosely and banks small yaku early, so beginners can out-score it. Normal takes the strongest captures and gambles with koi-koi when the pot is still small. Expert captures with an eye on its own yaku and presses its luck when many cards remain, banking once its score is high. The computer thinks entirely on your device, so the game works offline. Win the whole match to earn ranking points — Easy +10, Normal +30, Expert +100 — and sign in to record your best result on the leaderboard.

Strategy tips

• Watch the field before you play. Capturing a card also denies it to your opponent, so grabbing a bright or a ribbon you both want is often worth more than the points suggest.
• Aim your captures at a yaku. Three ribbons of the same colour, or the boar-deer-butterfly trio, turn a handful of ordinary captures into real points — collect with a plan rather than at random.
• Koi-koi when the reward outweighs the risk: you are only a card or two from a bigger yaku, plenty of cards remain, and your opponent's captures look harmless. Stop when your lead is good and few cards are left to change it.
• Remember the rain-man. Holding the November bright blocks your Sankō and turns four brights into the lower Ame-Shikō, so it can be worth capturing it just to keep it out of the computer's hands.

Frequently asked questions