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Koi-Koi
日本語Play

Credits and licences

Last updated

The hanafuda card pictures on this site and in the game are by Louie Mantia and すけじょ, with the card back and three revised faces by Spenĉjo, all from Wikimedia Commons under CC BY-SA 4.0. You may reuse and adapt them, commercially too, as long as you credit the authors, link the licence, say what you changed and share adapted pictures under the same licence. This page lists every file with its original, then the app icon, the historical pictures, sounds, fonts and software the game uses, and a note about this site.

Card art

The 48 card faces and the card back are SVG drawings from the set “SVG Hanafuda with traditional colors (black border)” on Wikimedia Commons. The faces are すけじょ’s traditional-colour version of Louie Mantia’s hanafuda cards, and Commons credits each of them to both. Spenĉjo drew the card back and uploaded the current revision of three faces. Every file is licensed CC BY-SA 4.0 by its authors, and the copies used here stay under that licence. It covers the pictures only, not the game’s code.

Who is credited for the 49 files
FilesAuthorsLicence
45 card facesLouie Mantia and すけじょCC BY-SA 4.0
3 card faces: the Bridge, the Maple blue tanzaku and the LightningLouie Mantia, すけじょ and SpenĉjoCC BY-SA 4.0
The card backSpenĉjoCC BY-SA 4.0

What was changed

The same changes were made to every file, and none of them alters the drawing:

  • Minified with SVGO 4.1.0 (default preset, multipass).
  • width and height attributes added, equal to the drawing’s own viewBox (976 × 1600), so that every browser can draw the file into a canvas. The pictures were not resized or cropped.
  • A comment added at the top of each file, naming the original, its authors, its Commons page and the licence.
  • Each file renamed after the card it shows, as the game names it (matsu_crane.svg is the Crane).

Rendered before and after, the files differ only in a few anti-aliased edge pixels. A plain-text copy of this list travels with the pictures as cards/CREDITS.md. The list of all 48 cards shows the same pictures month by month.

Faces by Louie Mantia and すけじょ

45 files, each licensed CC BY-SA 4.0 by Louie Mantia and すけじょ. The file name links to the copy used here; the original links to its page on Wikimedia Commons, where its history and licence are recorded.

Faces revised by Spenĉjo

Three faces are used in the revision Spenĉjo uploaded, so they are credited to Louie Mantia, すけじょ and Spenĉjo, CC BY-SA 4.0. The upload notes on Commons say what was changed:

  • Bridge (4 January 2026): “Added orange, for a more traditional and representative color scheme.”
  • Maple blue tanzaku (4 January 2026): “Changed yellow to dark gray, for a more traditional and representative color scheme.”
  • Lightning (28 December 2024): “Updated card art to a more traditional design, based on Louie Mantia’s original SVG and a public domain scan”.

The card back

By Spenĉjo, CC BY-SA 4.0. It is the face-down side of every card, at the table and in the home page scene.

Reusing the card pictures

You can download any card from this site (the file names above link to the files) or take the originals from Wikimedia Commons. CC BY-SA 4.0 lets you copy, share and adapt them for any purpose, commercial use included, on these conditions:

  1. Credit the authors. Louie Mantia and すけじょ for the faces; Spenĉjo for the back and, with them, for the three revised faces.
  2. Link the licence: creativecommons.org/licenses/by-sa/4.0.
  3. Say what you changed, and that the files you took from here were minified.
  4. Share alike. A picture you make from them, such as a recoloured card or a new drawing traced over one, must be licensed CC BY-SA 4.0 (or a compatible licence). This applies to the pictures, not to everything they appear next to: your own text or your game’s code can keep their own licence.
  5. Add no restrictions. Do not add terms or technical measures that stop others from using the pictures under the licence.

The licence covers the copyright in the drawings. It grants no trademark rights and does not mean that the authors endorse your use. The traditional hanafuda designs are far older than these drawings; what is licensed here is these particular drawings of them.

Images made from the card art

Some images made for this site include card pictures, for example the preview images shown when a page is shared on social media or in a chat. They are adaptations of the card art, so they are licensed CC BY-SA 4.0 too, with the same credit to Louie Mantia, すけじょ and Spenĉjo. The same applies to any screenshot of the game that shows the cards.

App icon, favicon and logo

The logo: a hanafuda card emoji with a gold edgeThe app icon: the same card on a black lacquer background

The app icon, the favicon, the header logo and the startup images all show the 🎴 “flower playing cards” emoji from Twemoji (v17.0.3), © 2019 Twitter, Inc and other contributors, licensed CC BY 4.0. The version used is the file 1f3b4.svg from jdecked/twemoji, the maintained continuation of Twitter’s Twemoji; the drawing dates from Twitter’s releases.

Changes: a gold edge was drawn around the card; for the app icons the card was scaled and placed on a lacquer-black background; the monochrome icon is reduced to a one-colour silhouette; everything was resized and rasterised to PNG and ICO. The adapted icons are licensed CC BY 4.0 as well. Twitter and the Twemoji maintainers do not endorse this game.

The four app shortcut icons (practice, play with a friend, rules, yaku) each draw one Lucide icon (bot, users, book-open, sparkles; ISC licence) in white on the same background.

Historical pictures

The history of hanafuda is illustrated with old cards photographed or scanned by others. Each is credited here as its Wikimedia Commons page gives it.

Sound effects

Every sound in the game is a cue from the “Zen” pack of UI SFX by Yuki Capital, dedicated to the public domain under CC0 1.0. No sound file is downloaded: the UI SFX runtime (MIT licence) synthesises each cue in the browser. Neither the sounds nor the runtime were changed. Both licences are reproduced in full in sounds/CREDITS.md.

Fonts

The text is set in Plus Jakarta Sans, and Japanese names such as the cards’ names in Noto Serif JP. Both are licensed under the SIL Open Font License 1.1 and are loaded from Google Fonts, which the privacy policy explains.

Software and libraries

The game is built with the software below. All of it is open source except GSAP, which is free to use under its own “no charge” licence; the avatar drawings and the sound pack are public-domain assets. The licences are the ones each package declares in its own files, for the versions the game uses.

In the game you download
SoftwareUsed forLicence
React, React DOMThe interface, and the pages of this siteMIT
Firebase JavaScript SDKGoogle sign-in, the databases, App CheckApache-2.0
noble-post-quantum, noble-curves, noble-hashes, noble-ciphersThe encryption and signatures of online matches (by Paul Miller)MIT
Radix UI primitivesDialogs, menus, tabs, popovers and tooltipsMIT
Lucide (lucide-react)Interface iconsISC
three.jsThe home page scene and the petals that celebrate a yaku or a winMIT
GSAP (with Flip)Dealing and moving the cards on the tableGSAP Standard “no charge” License
DiceBear (@dicebear/core, @dicebear/styles)Avatars, drawn in the browserMIT
DiceBear “Lorelei Neutral” (artwork by Lisa Wischofsky)The avatar drawingsCC0 1.0
UI SFX runtime (uisfx, by Yuki Capital)Plays the sound effects with Web AudioMIT
UI SFX “Zen” sound pack (Yuki Capital)The sound effects, synthesised in the browserCC0 1.0
WorkboxThe service worker (offline use)MIT
Tailwind CSS, tailwindcss-animateGenerates the stylesheetMIT
tailwind-merge, clsxCombining style classesMIT
class-variance-authorityButton and component variantsApache-2.0
Used to build and publish it (not sent to players)
SoftwareUsed forLicence
Vite, @vitejs/plugin-reactBuilds the appMIT
TypeScriptThe language the code is written inApache-2.0
PostCSS, AutoprefixerProcesses the stylesheetMIT
esbuild, tsxBundles the service worker; runs the build scriptsMIT
sharpRenders the icons and startup imagesApache-2.0
SVGOMinified the card picturesMIT
PlaywrightScreenshots and page checksApache-2.0
Firebase CLI (firebase-tools)Deploys the site and the security rulesMIT

About this site

Koi-Koi Online (花札こいこいオンライン) is a free version of Koi-Koi, the two-player hanafuda game (also written “koi koi” or “koikoi”), that runs in the browser: online against a friend after signing in with Google, or practice against the computer with no account needed. The guides on this site explain its rules, yaku and scoring, the cards and their history, in English and in Japanese; each language has its own text.

  • Where the rules come from. The guides describe the rules exactly as this game plays them, and mark every point where they differ from Nintendo’s published rules and common Japanese house rules; the house rules page compares them side by side. Each guide lists the sources it used.
  • Independent. This site is not affiliated with Nintendo or any card maker.
  • Last updated on 26 September 2026.
  • Your data. What the game stores, and why, is in the privacy policy. Common questions are answered in the FAQ.

Licences and references

  1. Attribution-ShareAlike 4.0 International (CC BY-SA 4.0). Creative Commons: The licence of the card pictures.
  2. Attribution 4.0 International (CC BY 4.0). Creative Commons: The licence of the Twemoji icon.
  3. CC0 1.0 Universal. Creative Commons: The licence of the avatar drawings and the sounds.
  4. Category:SVG Hanafuda with traditional colors (black border). Wikimedia Commons: The originals of the card pictures.
  5. Reusing content outside Wikimedia. Wikimedia Commons: How to credit Commons files.
  6. Recommended practices for attribution. Creative Commons
  7. jdecked/twemoji, v17.0.3. GitHub: The source of the 🎴 icon.
  8. SIL Open Font License 1.1. SIL International: The licence of both fonts.