Neoromance games are typically released with two versions at the same time--a regular version and a Premium Box version. The Premium Box versions tend to be priced 2,000yen more than the regular version (which is priced at the industry standard for games on that platform) and come packaged with a gift. In the past, the gifts have been collectibles (such as art boards, accessories, etc.) but in more recent releases, the bonus materials have been much improved. They usually include a CD or CD-ROM, and illustrations or information relevant to the game bound in gorgeously designed books. Premium box discs also have a picture label on them, rather than the standard mono-colour discs.

When the games go out-of-print, Koei will release a reprint version (KOEI The Best or KOEI Regular Series) that is much lower priced. The contents are exactly the same as the original regular edition, but the packaging is slightly different. This is the version you should get if you've joined the party late. Definitely worth the savings! By the way, out-of-print doesn't necessarily mean unavailable. Depending on how old (or how new) the game is, you can still find leftover stock in a lot of stores. Out-of-print just means that Koei stopped manufacturing it, because they're releasing the reprint version.