From the Store description:
This is a completely free, lightweight local EPUB format ebook reader, mainly designed for reading novels with illustrations.
***Books are not included in the app. You have to find and download books from the Internet on your own. If you do not know what EPUB is, DO NOT download this app.
Quite a common sense caveat there, though including a mini-store of a few royalty-free ebooks in the application would have been a good idea, just to get people off to a good start?
Anyway, here's LightReader in action on my IDOL 4 Pro:
First of all, LightReader is free, but do consider supporting the dev via the in-app buttons. There are no ads or similar, it's a clean experience; (right) grabbing a test EPUB ebook, via epubbooks.co.uk in Edge...
Having downloaded the EPUB book, just pick it in LightReader and it's added to your in-app library; (right) Note the transparency effect on the hamburger menu.
Reading away, ilustrations/cover included. Note (right) the 'next' control, which appears overlaid when you're at the bottom of the current 'page'.
The tools at the bottom of the screen allow comprehensive customisation to text rendering, from font, size, spacing, and so on, while (right) the theme settings allow for an eye-friendly night mode...
The hamburger menu is where you navigate around a book, here by chapter; (right) moving 'back' takes you to your library again.
An excellent little application and well worth downloading on any Windows 10 device.
You can grab LightReader UWP here in the Store, and you can grab EPUB ebooks from many places, start at epubbooks.co.uk?