Japanese Lookup for Decky
Japanese Lookup open over a visual novel, showing the captured line split into words with a definition below

Celeste — Maddy Makes Games, 2018

Japanese study on the Steam Deck

A plugin for Decky Loader that lets you scan and look up Japanese text from your games — all without leaving Gaming Mode.

Download latest release Install guide

How it works

  1. Capture area highlighted over Japanese dialogue text

    1. Scan the screen

    Press one of the back buttons to scan text.

  2. Word-by-word lookup panel open beside the game

    2. Review words

    Scanned text opens up in the side panel.

  3. QR code export screen for sending cards to Anki

    3. Add to Anki

    Add words to study later in Anki.

Phoenix Wright: Ace Attorney Trilogy — Capcom, 2014

Features

  • Stay in Gaming Mode

    Lookup happens in the sidebar menu. Scan, review, close when done.

  • Works offline

    OCR engine and dictionary are downloaded once and stay on the Deck. Nothing is sent anywhere.

  • Capture areas

    Drag and create multiple capture areas wherever text appears in-game, and assign a hotkey.

  • Send to Anki

    Save words locally while looking them up. Generate a QR code and send to AnkiMobile / AnkiDroid.

Install

If you already have Decky installed, setup should take less than 10 minutes.

The Power menu with "Switch to Desktop" highlighted Desktop Mode, decky.xyz open in the browser with the Download button The downloaded installer sitting in the Downloads folder in the file manager

Install Decky Loader

Skip this if you already have Decky.

  1. 1 Hold the Steam button → Power → Switch to Desktop.
  2. 2 Open a browser, go to decky.xyz, and download the installer.
  3. 3 Open it from your Downloads folder in the file manager — not the browser's download popup.
The GitHub release page on the Deck with the .zip asset highlighted

Download the plugin zip

On the Deck, open the latest release on GitHub and download japanese-lookup-vX.Y.Z.zip, or click the Download button on this page to get the latest version.

Download latest version

The file should go to Downloads, leave it there for now.

Quick Access open on the Decky tab (plug icon) Quick Access open on the Decky tab, gear icon top right The Developer Mode toggle at the bottom of General, turned on

Turn on Developer Mode

The plugin isn't on the Decky store, so it's installed from the zip.

  1. 1 Press Quick Access (…) → the Decky tab (plug icon).
  2. 2 Press the gear icon → General.
  3. 3 Turn on Developer Mode at the bottom.
The Developer tab in Decky settings with "Install Plugin from ZIP File" The in-app file browser open on Downloads with the plugin .zip The Decky tab listing Japanese Lookup after install

Install from zip

  1. 1 Open the Developer tab in Decky settings (Developer mode must be enabled).
  2. 2 Press Install from zip, browse to Downloads (or wherever you placed the ZIP), and select the file.
  3. 3 Wait for it to finish, then check the Decky tab for Japanese Lookup.

If it doesn't show up right away, restart the Deck.

The Japanese Lookup panel on first open, showing the one-time setup buttons

First launch

Open Quick Access (…) → Decky → Japanese Lookup. With Wi-Fi on, press each download button and wait for it to finish before the next — they appear one at a time as each step completes:

Install lookup runtime~60 MB
Download dictionary (Jitendex)~70 MB
Install OCR runtime~400 MB
Download OCR models~22 MB

The OCR runtime takes a few minutes. The buttons disappear once everything is in place. Start a game and press L5

Updating is the same steps with the newer zip — settings, dictionary, and Anki queue are kept. Prefer to build it yourself, or want to change the code? See Install from source in the README.

Questions

Does it need internet?

Only for the one-time downloads on first launch, then it works fully offline.

Which games does it work with?

While the OCR can transcribe any text, it works best for games with dialog boxes. You can create multiple capture areas if text appears in different locations.

Pressing the back buttons does nothing

Check that the capture areas are setup for the current game, and that a hotkey is assigned to them.

It says "No text found" or "Accuracy low".

Check to make sure the capture area is correctly positioned over the text. However, if the font is overly stylized, the OCR may not be able to recognize it.

The QR code won't open on my phone.

Phone and Deck need to be on the same Wi-Fi network. The link expires after about five minutes — press Export via QR code again for a fresh one.

Can I use Yomitan instead of the built-in lookup?

Yes. Every captured line is also shown on a local page, found under Advanced settings → Show debug info

How much space does it take, and how do I remove it?

About 800 MB once the OCR engine and dictionary are downloaded. Advanced settings → Delete downloaded data frees that space but keeps the plugin. Uninstalling from Decky's plugin list should automatically remove those files as well.

Plugin data is stored in /home/deck/homebrew/data/japanese-lookup/.

How do I update the plugin?

Download the new version and install from ZIP through Decky. The shared dependencies (OCR engine, dictionary, etc) will be accessible to the newer version.

Does the plugin support translations?

No, as a study-focused plugin, only dictionary lookups are supported. For full translation, consider using Decky-Translator, which is also available directly on the Decky Plugin Store.

Where does the dictionary data come from?

The plugin ships no dictionary. On first launch it downloads Jitendex, which is built from JMdict by the EDRDG, Tatoeba example sentences, and JmdictFurigana. Full attribution and licences are in the README.