DjVu (originating from the term "déjà vu") is a document format designed as an alternative to PDF. This format can compress multiple images into a single file without losing quality. To view DjVu files, you need specialized software on your computer. Fortunately, this software is completely free.
Steps
Install the Software

You need to understand the software's functionality. DjVu is a document file format similar to PDF. This type of file requires specialized software to open. Another way to access this format is by using a browser plugin. This plugin allows you to open DjVu files directly in your web browser. You can also use a standalone viewer included with the plugin software.

Access cuminas.jp/downloads/download/?pid=1 using your web browser. This is a Japanese website, but it provides instructions in English.

Select your operating system from the dropdown menu at the top of the page. This ensures you download the correct installer for your current OS. Click here if you need to check whether your system is 32-bit or 64-bit.

Click the 次へ button below the dropdown menus.

Click the 同意してダウンロード button to accept the terms of the agreement. The installer file will begin downloading.

Run the installer and follow the on-screen instructions to install the DjVu software. You can mostly stick to the default settings, as there is no bundled adware included.
View DjVu Files

Double-click the DjVu file. After installing the software as described earlier, the DjVu file will automatically open in the reader application.

Interact with the file. The reader functions like most document viewers. You can navigate between pages, zoom in and out, print, and more.
- Editing DjVu files is not possible within the reader or using the plugin. If editing is necessary, search online for methods to modify DjVu files.

and paste sections of the document. Click on the "Selection" menu and choose "Select Region." You can then drag the selection box to any part of the document.
- the selected area by clicking "Selection" → "." Alternatively, press Ctrl+C (Windows) or ⌘ Cmd+C (Mac).
- Paste the selection into another document. The selected area will be pasted as a PNG file.

Open DjVu files in your web browser. Once the software is installed, the accompanying plugin will also be installed in all browsers on your computer (except Google Chrome). The browser plugin offers similar functionality to the standalone viewer.
- Drag the DjVu file into the browser window. Depending on the browser, you may be prompted to allow the DjVu plugin to run. Alternatively, right-click the DjVu file, select "Open With," and choose your browser from the list of applications.
Create and Edit DjVu Files

Download DjVu Solo. This free software allows you to create new DjVu files from images on your computer or scanner.
- You can download DjVu Solo from djvu.org/resources/, under the "Old (but useful)" section.

Run the installer. Most users can proceed with the default settings (no adware included).

Launch DjVu Solo. You can find the application in the Start menu or by searching for "DjVu Solo."

Add the first image file you want to use. You can drag and drop images into the DjVu Solo window or click the Scan button at the top to scan documents using a scanner.

Add more images by right-clicking on a thumbnail and selecting "Insert Page(s) After." Click the file type menu and choose "All Supported Image Files." You can add multiple images at once if desired.

Rearrange the pages. You can drag and drop thumbnails to reorder the pages as needed.

Create the DjVu file. Once satisfied with the page order, click "File" → "Encode As DjVu." Then, select "Bundled" (if you don't plan to use the DjVu file for web creation).

Use DjVu Solo to edit existing DjVu files. You can open DjVu files in DjVu Solo to rearrange, delete, or add pages.
- Open the DjVu file in DjVu Solo.
- Delete a page by right-clicking its thumbnail and selecting "Delete."
- Add new pages by right-clicking a reference thumbnail and choosing "Insert Page(s) After" or "Insert Page(s) Before." You can browse for image files on your computer to add.
- Reorder pages by dragging and dropping thumbnails.