Koi-Koi (こいこい)

A traditional Japanese hanafuda (flower card) game for 2 players.

Cards

Hanafuda uses 48 cards: 12 months × 4 cards each. Cards are classified into 4 types:

• Bright (光) — 5 cards, most valuable
• Animal/Seed (種) — 9 cards
• Ribbon (短冊) — 10 cards (3 red, 3 blue, 4 plain)
• Plain (カス) — 24 cards

Setup

• Each player receives 8 cards in hand
• 8 cards are placed face-up on the field
• Remaining 24 cards form the draw pile

Turn Structure

Each turn consists of two steps:

1. Play from hand — Play one card from your hand onto the field

   • If it matches a field card (same month), capture both cards
   • If 2 field cards match, choose which one to capture
   • If 3 field cards match, capture all 3 (completing the month)
   • If no match, the card stays on the field

2. Draw from deck — Draw one card from the deck

   • Same matching rules apply as above

Yaku (Scoring Combinations)

When you collect cards that form a yaku (combination), you choose:

• Koi-Koi — Continue playing to aim for a higher score (risky!)
• Shōbu — Stop and score your points, ending the round

Yaku List

Yaku	Cards Required	Points
Five Brights	All 5 bright cards	15
Four Brights	4 brights (no Rain Man)	8
Rainy Four Brights	4 brights (with Rain Man)	7
Three Brights	3 brights (no Rain Man)	6
Boar-Deer-Butterfly	Boar + Deer + Butterfly	5
Red Ribbons	3 red ribbon cards	6
Blue Ribbons	3 blue ribbon cards	6
Flower Viewing Sake	Cherry Curtain + Sake Cup	5
Moon Viewing Sake	Moon + Sake Cup	5
Animals	5+ animal cards	1 (+1 per extra)
Ribbons	5+ ribbon cards	1 (+1 per extra)
Plains	10+ plain cards	1 (+1 per extra)

Scoring

• If your opponent declared Koi-Koi and you win, your score is doubled
• With the "7+ Double" variant, scores of 7 or more are doubled again

Game Length

A full game consists of 12 rounds. The player with the highest total score wins.

Variants

• Flower/Moon Viewing Sake — Enable or disable the Hanami-zake and Tsukimi-zake yaku
• 7+ Points Double — Scores of 7 or more are doubled