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