Here is the full list of all 15 Rosenkreuzstilette achievements.
Finish the game as Grolla Seyfarth.
Finish the game as Grolla in 60 minutes or less.
Defeat the Deviled Egg without taking any damage.
Max out your reserve of Extra Lives.
Run out of time while facing Zorne Zeppelin.
Max out your supply of Cross Tanks.
Add the spunky Lilli to your arsenal.
Collect all 100 coins in Schwer-Muta's domain.
Defeat a boss with only one point of Vitality left.
Finish the game as Spiritia Rosenberg.
Finish the game as Spiritia in 60 minutes or less.
Defeat Count Zeppelin.
Defeat the 8 numbered members of Rosenkreuzstilette.
Complete a stage without taking any damage.
Complete the Prologue stage.