Chrome extension · v0.2.0
After you agree, the extension syncs your own YouTube sign-in to Bunmyaku.
For each video you submit, the server uses it to briefly retrieve the audio and frames
and make your subtitles.
You watch in YouTube’s embedded player and never receive a video file.
You can revoke it at any time. Privacy policy
Desktop Chrome or Edge · The Chrome Web Store version is in review;
you can also install it manually with the steps below.
Phone and tablet browsers can’t run extensions. Open this page in Chrome or Edge on a computer.
Checked live on this page. No cookie contents are read or shown.
Install · 5 steps · about two minutes
The Chrome Web Store version is in review.
To install it manually, Chrome loads it from a folder in Developer mode.
Each picture acts out the step beside it.
01Install · step 1
Download bunmyaku-extension.zip (v0.2.0 · 36.7 KB).
Windows: right-click it → “Extract All”. macOS: double-click it.
You get a bunmyaku-extension folder. Open it; right inside are:
Keep the folder somewhere permanent, such as Documents. Chrome loads the extension from it every time, so don’t delete or move it after installing.
Result: A bunmyaku-extension folder with manifest.json directly inside
02Install · step 2
Type this address into the address bar and press Enter.
Web pages can’t open chrome:// addresses directly, so copy it from here.
In Edge, the address is:
Result: The Extensions page is open
03Install · step 3
The “Developer mode” switch is at the top right of the Extensions page.
The “Load unpacked” button only shows up after you turn it on.
In Edge, the “Developer mode” switch is in the left sidebar,
and the button is also called “Load unpacked”.
Result: The “Load unpacked” button appears
04Install · step 4
Click “Load unpacked” and choose the bunmyaku-extension folder — the one with manifest.json directly inside.
Then click “Select Folder” (on a Mac, “Select”).
If Chrome says the manifest file is missing, you picked the folder one level up. Choose the inner one.
Result: “Bunmyaku Sign-in Sync” 0.2.0 appears in the list, switched on
05Install · step 5
Click the puzzle-piece Extensions icon to the right of the address bar,
then the pin next to “Bunmyaku Sign-in Sync”.
The extension’s icon is Bunmyaku’s seal: a red square with “文”.
Chrome may now and then warn you about developer-mode extensions. Keep this one; don’t turn it off.
Result: A red “文” icon sits in your toolbar
Use · sync your YouTube sign-in
The sign-in is kept for at most 7 days;
sync again when it runs out
or YouTube expires it.
06Use · step 6
You can sync right here: this is a Bunmyaku page, and the check at the top updates when the panel closes.
Result: “Synced: N cookies.”
07Use · step 7
YouTube expires sign-ins from time to time.
When Bunmyaku confirms YouTube has rejected the stored sign-in, the app shows “Your YouTube sign-in has expired. Click the Bunmyaku extension in your browser toolbar, sync again, then retry.”
The extension’s panel pops up by itself with “Your YouTube sign-in has expired. Click the Bunmyaku extension in the browser toolbar, then sync again.”
A red “!” marks the extension icon on the tab where the problem was found. It disappears after you sync again in that tab.
Result: The red “!” on that tab is gone
08Use · step 8
Click the icon to open the panel and press “Revoke and delete”. The server deletes the stored sign-in immediately.
If you don’t revoke it, the sign-in is kept for at most 7 days.
To uninstall the extension, open chrome://extensions and click “Remove” on the Bunmyaku card.
Result: “Revoked. The server no longer keeps your YouTube sign-in.”
09Use · step 9
Download the new zip and replace the files in the same folder.
Then press the reload arrow on the Bunmyaku card in chrome://extensions, and reload any open Bunmyaku tabs.
A tab you haven’t reloaded says “The Bunmyaku extension was updated. Press F5 to reload this page, then click the toolbar icon.”
This page offers version 0.2.0. If your card shows the same number, you’re up to date.
Result: Your card shows 0.2.0
Where your sign-in goes
Nothing moves until you click,
and each stop does exactly one job.
You can revoke it from the panel at any time. Privacy policy
The YouTube sign-in in your browser
You click the icon
a one-time, 15-second permission
The extension
reads only youtube.com cookies; its background part never goes online
Never goes to: Other sites’ cookies
The Bunmyaku page
the extension’s panel on the page sends a same-origin request carrying your own Bunmyaku sign-in
Never goes to: Third parties
The server
stores it encrypted (AES-GCM, a dedicated key) for at most 7 days
Never goes to: Other users
Decrypted only while your own video is processed
deleted when the job ends
Only for subtitles of the videos you submit
Troubleshooting
Most questions are the panel’s own message.
Where the older version 0.1.1 says it differently,
that is listed alongside.
Only to make subtitles for videos you submit.
While a video is processed, the server uses it to briefly retrieve that video’s audio and frames.
That includes unlisted, members-only and age-restricted videos your own account can already watch;
their subtitles stay private to your account.
Playback stays in YouTube’s embedded player. Bunmyaku has no download feature, and you never receive a video file.
The icon only works on Bunmyaku pages. If the tab was opened before you installed the extension, reload it and click again.
Read the line under the buttons.
“Click the Bunmyaku icon in the browser toolbar first, then press Agree and sync within 15 seconds.” means the panel has no permission yet: click the toolbar icon once, and the button lights up.
If the panel says “Sign in to Bunmyaku first.” or “Verify your account's email address first.”, both buttons stay grey until you do that; then one click on the toolbar icon brings them back.
15 seconds passed, or this permission was already used.
Each permission covers one press of sync, whether that press succeeded or failed.
Click the toolbar icon once more (the panel stays open), then press sync within 15 seconds.
Still on 0.1.1? Update it (step 9): the new version tells you in the panel what to do.
Both buttons stay grey until you sign in to Bunmyaku at getbunmyaku.com in this browser. Log in
Each web address keeps its own sign-in, so sign in here even if you did elsewhere.
Then come back and click the toolbar icon once: the panel checks again, stays open, and the buttons light up. Now sync.
The same fix applies to “Your Bunmyaku session has expired. Sign in to Bunmyaku again.”
New here? Bunmyaku is invitation-only for now. How to get an account
Verify your email address first, then come back and sync.
Make sure you’re signed in to YouTube in this same browser and profile, in a normal window (incognito doesn’t count).
Then click the toolbar icon once, and press sync within 15 seconds.
Syncing is rate-limited. Wait a little.
Then click the toolbar icon once, and press sync within 15 seconds.
The extension was just reloaded or updated, and pages that were already open lost touch with it. Press F5 to reload the page, then click the toolbar icon.
No. Phone and tablet browsers can’t run Chrome extensions; use Chrome or Edge on a computer.
Not supported. Use Chrome or Edge on a computer.