Here in the West, we’re all thoroughly familiar with the idea of furthering your enjoyment of a game by purchasing additional merchandise to celebrate your love of it.
Depending on the game, we might get action figures, posters, comics, books, soundtrack CDs… but rarely something “extra” in the original medium, unless a sequel comes along, or perhaps some DLC.
One thing that Japanese developers and publishers like to do — and which we’re seeing increasing numbers of localised for English-speaking audiences — is produce a “fandisc” for a popular work. And while the idea may seem self-explanatory, I’ve seen plenty of examples of people who don’t quite “get” it.