CDJapan just launched a new digital ebook service this week, with over 10,000 manga, books, photo books, light novels, and art books in their library available internationally. The company actually offers close to 50,000, but most are geo-restricted to Japan.
Most of the digital comic books you buy can be read on the PC or via the Android and iOS apps. The apps are free and have panel guided view technology that isolates specific panels. You can easily organize your ebooks on your devices by creating bookshelves. Drag ebooks from bookshelves to other bookshelves. If you are running low on memory due to the larger file sizes of comics, you can just delete them. All purchases are stored in the cloud, so you can download them at a later date, or sync purchases to different tablets.
Most of the comics are all in Japanese, so English speaking customers might not find a ton of value. Still, Manga tends to be very popular and this company offers a very wide selection that might appeal to the mobile centric.