The The Dark Sea DLC Add-on for AURA: Hentai Cards has 7 achievements.
Visit the Dark Forest
Complete Dryad's story arc
Spare "The Truth"
Destroy "The Truth"
Complete all quests in the "The Dark Sea" DLC
Finish the story of the "The Dark Sea" DLC and achieve the bad ending
Finish the story of the "The Dark Sea" DLC and achieve the good ending