Yakuyomi is a fork of mihon that translates manga as you download or read it — Japanese to Traditional Chinese by default, any language pair configurable. Text detection, OCR, and removal run on the device (NCNN + ONNX Runtime); only the translation step calls a cloud LLM. The translation engine is a separate repo, yakuyomi-engine, pulled in here as a submodule.
Text over art — hair, faces, backgrounds — is where box-fill / overlay translators fall apart. Yakuyomi erases the original and reconstructs the artwork (3), then typesets the translation back in (4).
Everything below is on top of stock mihon — at a glance, what you get here that other forks don't:
Translation
- Real inpainting, not overlays — other translation forks paint a box over the text or stamp new text on top. Yakuyomi erases the original and reconstructs the artwork (AOT-GAN inpainting) before typesetting the translation back into the bubble.
- On-device pipeline (NCNN + int8) — detection (a DBNet model) and text removal run on NCNN's mobile kernels, OCR on an int8-quantized model (~3.6× faster than fp32 at 96.7% parity). Moving off ONNX Runtime shrank the model set from ~470 MB to ~200 MB, and the DBNet detector reads ~1.6–2.5× more text correctly than the one it replaced. On a Snapdragon 8 Gen 3, detection + OCR over 6 representative pages (161 text boxes) run in ~10.3 s and read back 99.4% of the text. Pure CPU (GPU/NPU was tried and doesn't help these models). Only the LLM translation call leaves your device; no image ever leaves the phone.
- Cross-page pipeline (~2× faster) — pages translate concurrently: while one page waits on the cloud LLM, the next page's on-device detection / OCR / removal is already running. At a shallow depth this reaches the network-bound ceiling — roughly double the throughput of live / fast-removal translation.
- Two workflows — translate-on-download (whole chapters in the background) and live translation while you read. A page is overwritten only when its translation succeeds; nothing is ever replaced with something worse.
- Your provider, your key — any OpenAI-compatible LLM (DeepSeek by default; OpenAI, Gemini, Groq, Qwen, OpenRouter, self-hosted Sakura, custom), per-provider encrypted keys, live model list (providers doc).
- Your models — the model set (NCNN detector + inpaint pairs, int8 OCR, ~200 MB) downloads in one tap with sha256 verification, or you supply them manually (models doc).
- Quality knobs — two text-removal modes (fast flat-fill / AI inpainting), vertical/horizontal typesetting, ~20 tunable parameters. No telemetry.
Live translation as you read, one-tap re-render of the text-removal method, and a per-manga translation queue — expand chapters, jump a title to the front, pause it.
Capture
- Built-in browser, saved as a chapter — open any address in Yakuyomi's full-screen browser and save what it renders as page images in your local library. The result is an ordinary local manga: read it, file it in a category, and run it through the same on-device OCR and translation pipeline as everything else.
- Semi-automatic or hands-free — a frame-diff detector (the screen settled and the content actually changed) saves each new page by itself while you swipe, skipping the near-blank frames a page shows while it loads. Set a tap position once and it turns the pages itself — a simulated touch, no scripts injected into the page — for a whole chapter unattended.
- Three ways it stops — the page count you entered is reached, two taps in a row leave the screen unchanged (last page, or the tap position is off), or you stop it yourself. Whichever it was, the review screen says so.
- Per-site settings, remembered by domain — canvas width (narrow the page on a wide screen so a full page fits in one shot), draggable trim lines for a site's header and footer (marked by a persistent grey overlay), auto-trim for the blank margins that spreads and short pages leave behind, and the tap position and delay used for automatic page turns.
- Review before it becomes a chapter — stopping opens a three-column thumbnail grid: tick pages to delete, re-capture a single page (it reopens the address that page came from), insert a page you missed between two others, keep capturing, or save — saved pages are renumbered into a gapless sequence. The title can be lifted from the page title, the cover is a drag-to-frame crop, and Continue capturing on a local manga's detail page reopens the original address and appends to the same book.
- What it can't capture — content the system marks as protected (DRM) comes out blank. That's by design; Yakuyomi doesn't work around it.
Hands-free capture — the browser turns the page, every settled frame is saved — a review grid to fix things up before they become a chapter, and per-site setup: canvas width, trim lines, and where to tap to turn the page.
Reader
- Auto webtoon detection — long vertical strips switch to continuous-vertical reading on their own; a per-manga choice always wins.
- In-reader chapter list — jump to any chapter from a list inside the reader, without backing out to the details page.
- E-ink mode — one tap turns on grayscale, a white theme, and white-flash page refresh for e-readers.
- Cover in progress notifications — the background-translation notification shows the chapter's full cover, not just an icon.
An in-reader chapter list and a one-tap e-ink mode.
Library
- Drag to reorder — a "Manual" library sort: long-press a cover and drag to set your own order, saved per category.
- Single-list collapsible categories — show the whole library as one scrolling list with sticky, tap-to-collapse category headers, instead of swipeable tabs.
- Cover-based theme — optionally tint a manga's detail screen with colors pulled from its cover.
- Translated badge & filter — a cover badge counts translated chapters; filter the library by translation state.
- Per-category controls — in the single-list view, every category header shows its own sort field and direction (tap to sort), long-press the name to rename, and a ≡ button reorders categories in a drag dialog. Drag a cover within its category to reorder, or past the boundary to move it to another.
- Remember last categories — adding a new title pre-checks the categories you picked last time, so you just hit Add (toggle in Library settings).
- Pull-to-refresh toggle — off by default so a stray swipe-down can't start a full library update; one switch gates the library, the details page, and the Updates tab together.
- Reading & translation statistics — the Statistics screen adds per-day reading activity (chapters and titles read, backfilled from your history) and translation usage (chapters/pages plus LLM token counts), each with today / 7-day / 30-day / all views.
Drag covers into your own order, collapse the whole library into one list of tap-to-collapse categories, and tint the detail screen to each cover's colors.
Per-category controls in the single-list view — give each category its own sort (tap the header), and rename or reorder categories.
Drag a cover to another category, and see per-day statistics — reading activity + translation usage (today / 7-day / 30-day / all).
Browse & catch-up
- Global browse filter — filter any source's results by in your library / started reading, applied instantly to the loaded list without re-fetching.
- Per-source anchor — mark a title as your "last processed point", and a one-tap background task crawls the Latest feed down to it — a few pages at a time, spread over minutes and resumable across app kills/reboots (paced so the source never bans you) — saving everything above the anchor as an offline snapshot. The snapshot is trimmed to the anchor (older entries drop off, the anchor stays last), a jump-to-anchor button takes you straight to it, and the anchor stays visible with a grey flag even when the global filter would hide it.
- Offline snapshot — save a source's currently-loaded list and browse it later with zero network (lighter on the source, ban-safe).
- Background fetch — fetching details and chapters for a large filtered list (so they show up correctly, get update info, and can be downloaded) used to pin you to the browse screen until it finished. Now: narrow the list with the filters above, tap Fetch details, and walk away — it runs in the background with a progress notification you can cancel from anywhere. One title is fetched at a time (throttled to stay ban-safe); while it runs, the button shows progress instead of letting you start a second one.
- Ban-safe pacing — sources that punish aggressive scraping are handled two ways. Browsing/searching doesn't prefetch pages ahead, so the number of requests tracks your actual scrolling — this alone stops sensitive sources (e.g. Manhuagui) from banning you on the second search page. And page loads / background fetches are spaced with randomized jitter rather than a robotic fixed interval (itself a bot signal). The minimum page-load interval stays configurable.
- Source-list tweaks — tapping a source opens its Latest list directly (on by default, hiding the now-redundant per-source Latest button); optionally hide the "recently used" row and the local source.
- Auto-refresh on open — optionally refresh a manga's chapters every time you open it.
Search
- Floating search — an optional one-handed search pill at the bottom that collapses to a ball when idle; long-press the ball for a quick menu (with filter nearest your thumb), no need to expand the bar first.
- Saved searches & advanced syntax — save a search to recall later;
,= AND,-= exclude, andgenre:/author:/artist:prefixes for precise library queries. - Compact navigation bar — an icons-only, tighter bottom bar option.
A one-handed floating search that idles into a ball, and a global browse filter on the loaded list.
Catch up on any source — save its loaded list as an offline snapshot, and auto-load the Latest feed down to your anchor.
Large screens & foldables
Fold → single page; unfold → double-page spread. And the translation queue turns into a two-pane master-detail layout on tablets / unfolded foldables. Both pages translated on-device.
- Adaptive grid cover size — library and browse columns auto-fit the actual screen width (phone, tablet, folded/unfolded foldable, split-screen). Pick a size by how many fit per row and it scales to every width.
- Tablet reading mode — a separate reading mode for when you're on a large screen / unfolded (e.g. continuous-vertical on the phone, right-to-left paged on the tablet), following the system Tablet UI setting.
- Double-page spread — read two pages side by side on tablets/large screens (right-to-left or left-to-right). Wide/spread pages get their own full-width page instead of being squeezed in; a manual shift button aligns spreads split across the pairing. It's a reading mode, so it pairs with the tablet reading-mode setting above. Fill mode (fit width / fit height) and alignment are configurable under Settings → Reader → Double-page.
- Collapsible description — choose whether a manga's description opens expanded or collapsed.
Everything else is mihon — library, sources/extensions, downloads, trackers, backups, the reader.
Grab the latest signed APK from the Releases page. Take the arm64-v8a build for most phones, or universal if unsure. No build step needed — you only need to build from source if you want to.
Four of the five stages run on the device; only translation leaves it. Each stage below carries the settings that tune it, so you know which knob affects which step (full list in PARAMETERS; the pipeline design lives in yakuyomi-engine).
flowchart TD
P["漫畫頁 · Manga page"] --> DET
DET["① 偵測 Detection · NCNN"] --> OCR["② OCR · int8 ONNX"]
OCR --> TR["③ 翻譯 Translate · ☁ cloud LLM"]
OCR --> INP["④ 去字 Text removal · NCNN AOT-GAN"]
TR --> RND
INP --> RND["⑤ 排版 Typeset"]
RND --> OUT["翻好的頁 · Translated page"]
DET -. 設定 settings .-> Do["辨識尺寸 · 偵測銳利化<br/>Detection size · Sharpen input"]
OCR -.-> Oo["OCR 外擴 · 內插法 · 銳利化 · 信心門檻 · 跳過 SFX<br/>Crop pad · Interpolation · Sharpen · Min confidence · Skip SFX"]
TR -.-> To["供應商·金鑰·模型 · 語言 · 溫度 · 下載翻/即時翻<br/>Provider·key·model · Languages · Temperature · On-download/Live"]
INP -.-> Io["去字方法 · 解析度 · 遮罩膨脹 · 外擴<br/>Method · Resolution · Mask dilation · Padding"]
RND -.-> Ro["方向 · 文字色 · 描邊 · 字級 · 縱中橫<br/>Orientation · Colour · Outline · Font size · Tate-chu-yoko"]
classDef opt fill:#f6f8fa,stroke:#d0d7de,color:#57606a;
class Do,Oo,To,Io,Ro opt;
Two layers of concurrency keep it fast. Within a page, text removal (CPU) runs while the translation request is in flight (network) — the page pays only the longer of the two, not their sum. Across pages, the engine pipelines: while page N waits on the LLM, page N+1's detection / OCR / removal already run on-device. With the fast box-fill removal this reaches the network-bound ceiling — about 2× the sequential rate.
The heavy vision work — detection, OCR, inpainting — runs on your phone (private, free, offline). Only the OCR'd text is sent to a cloud LLM (bring your own key), because for the translation step the cloud is almost free, faster, higher quality, and works on any phone.
Real usage with DeepSeek (deepseek-v4-flash), 9 days of heavy reading:
| DeepSeek — 9 days, heavy use | cost |
|---|---|
| ~5,000 pages · ~200 chapters · ~2.7M tokens | ≈ $0.20 |
| — per chapter | ~$0.001 |
| — per month at that pace | ~$0.67 |
Running the LLM on-device instead would save that ~$0.001 per chapter — but cost you 10–40× the wait per page, plus heat, battery, gigabytes of RAM, and a flagship phone:
| ☁ Cloud DeepSeek | On-device 1.5B | 7B | 14B | |
|---|---|---|---|---|
| per page — translation step¹ | ~1–3s | ~10s | ~20–40s | ~40–80s |
| translation quality | high (frontier) | weak | mid | good |
| resident RAM | 0 | ~1.5 GB | ~4.5 GB | ~9 GB |
| hardware needed | any phone | mid-range+ | 8 GB+ RAM | 16 GB flagship |
| power / heat | none (off-device) | medium | high | very high |
| money | ~$0.001/chapter | $0 | $0 | $0 |
| offline | ✗ | ✓ | ✓ | ✓ |
¹ Translation (LLM) step only — detection / OCR / inpaint still run on-device in every case, so a page is not "one finished image per second". On-device figures are estimates (dashed in the chart), not measured.
So Yakuyomi keeps the expensive vision work on-device and sends only text to a cloud LLM: translation ends up effectively free, fast and high-quality, on any phone — while detection / OCR / inpainting keep your images on the device.
The engine is a git submodule, so clone recursively:
git clone --recurse-submodules https://github.com/joyeli/Yakuyomi.git
cd Yakuyomi
./gradlew :app:assembleDebugThe engine is wired in via a Gradle composite build (includeBuild). No model weights or API keys are needed to build — you download the models and enter your LLM key inside the app.
Yakuyomi is a real mihon fork: it tracks mihon's reader and adds only the integration layer — a download/translate hook, translation settings, model management, and branding. The on-device ML is isolated in the engine submodule, so the reader stays mihon-shaped and the engine can be tested on its own.
The developers of this application do not have any affiliation with the content providers available, and this application hosts zero content.
GPL-3.0 — see LICENSE-YAKUYOMI.md. Yakuyomi combines mihon (Apache-2.0, see LICENSE) with the translation engine, which ports manga-image-translator's prompt, parameter schema, and grouping, and uses GPL-3.0 model weights; the combined app is therefore GPL-3.0. mihon's Apache-2.0 license and attribution are retained.
- mihon — the reader this forks (Apache-2.0)
- yakuyomi-engine — the on-device translation engine
- manga-image-translator — prompt and behaviour reference
- model weights — DBNet detection, 48px CTC OCR, and AOT-GAN inpaint — from manga-image-translator; the on-device files are our own builds of those weights (NCNN conversions for detection and inpaint, an int8-quantized ONNX export for OCR)