If you get the membership, you can read all of a bunch of different light novels on a tablet:
Any new series added, starting with volume 1
The latest volume of ongoing series
A rotating set of catch-up releases every month, see "This Month’s Catchup Series" at the bottom of the main page
I :heart: my Kindle for reading books, but my iPad works well for reading the content above. If you don't want to spend the money for an iPad, a Lenovo Tab will do the job, either 8" or 10". You could also gamble on some no-name tablet from Amazon. Or a Fire tablet on sale (8" refurb is $55) but it comes with their own "Silk" browser which might or might not work with JNC -- though you can side-load Firefox or Chrome.