Looking for an app that allows you to download and read manga on your smartphone? So take a look at Tachiyomi. It is a manga reader that is available in the alternative Android store, F-Droid, that we can download for free (from here) and that It will allow us to read Manga from different sources known as KissManga, Mangafox, Batoto, among others.. The app even syncs with MyAnimeList in case we want to keep track of the manga read.
Tachiyomi offers everything we would look for in a Mangas app on Android, dark / light themes, the option to categorize the sleeves to have a tidier library, automatic updates to search for new manga. We can even synchronize our library in the cloud to have everything stored in some existing service (Dropbox, Google Drive, etc.).
To use it, we only need to download the Tachiyomi app (through F-Droid, which is recommended to get updates, or download the direct APK), install it, go to Catalogs, and search for the Magnas that interest us. The app even allows us to use a Smart Fit, where the Manga panels are automatically detected to show us segments of the entire page, making it much more readable on a smartphone. This is a great relief, because instead of seeing the manga in full screen and we having to manually zoom with our fingers to see all the content, we simply let the app do it for us!