Calibre is a eBook management library for the computer or ereader. The power of it comes from the plugins that helps to work with various file formats.
The eBooks or comics or manga can be named, filed and categorized in almost any way you want. Caution if you have OCD, this can be a rabbit hole.
I used Calibre to group my books into series or collections. This will aid reading on the Kobo reader. To increase the performance, the books are converted from epub to kepub format before sending it to the reader via USB. All this is done invisibly by a plugin.
As a library management tool, there will be lots of books and metadata that you treasure. Calibre can work with Dropbox, Onedrive and Google Drive. This will give you some peace of mind.
An ereader can store thousands of files. If the ebook is poorly formatted or just simply large in size, the reading experience will not be great. Using Calibre build-in fonts in the ebook can be removed to reduce space, that is if you are not particular about how the text look. It can also help to compress images to make the ebook even smaller.