There are several "New Mission Addition Packs" (labeled 1 through 4) that expand the game's story and recruitment options [1, 3].
One segment of a larger installation package for the PC or emulated version [1]. Dark.Rose.Valkyrie.part3.rar
If you are looking for this specific file, it is likely one of the following: There are several "New Mission Addition Packs" (labeled
A collection of game assets, soundtracks, or videos related to the "Valkyrie" project [1]. Dark.Rose.Valkyrie.part3.rar
The game is a Japanese RPG set in an (the Taisho era) [2].