This was written to go alone with Ara's pre-manga series The Good Ol' Days:

Behind every good officer, there are hard-working, uncredited NCOs. The new major and his newest agent have their first disagreement over orders.

After twenty-five years of resisting Eroica's advances, Klaus finally gives in, only to have the Earl drop a bombshell that convinces the Major that the world he knew ended without his knowledge and was replaced with a cruel parody. Nobody breathe or the house of cards will collapse.

Spoilers: Through “Emperor Waltz” with references to the hiatus after that story.