What would you do if you discovered that you are only a human ... part of the time?

Luna V. Moon thinks that she's an ordinary girl. She lives in a quiet room at an empty orphanage. She is tended to by a motherly tutor, Eva, and a harsh man named Mr. Shrude. Mr. Shrude is a gruff taskmaster who puts Luna through intense physical training. The rooftops around the orphanage are Luna's lone escape, and the stars are her only real company. Every night, Luna takes one last look at the night sky, drinks a tall glass of chocolate milk, and falls asleep.

"Don't drink the chocolate milk." A mysterious girl claiming to be Luna's long-lost sister breaks into her room to deliver a puzzling message. Luna obeys this ominous warning and discovers that nothing is as it seems.

Would you heed the warning? Or would you drink the chocolate milk?