Millium Orion is a member of Class VII in the later chapters, and is a major character in the Cold Steel arc. Millium is a member of the Imperial Army's intelligence division, which eventually sent her to Thors Military Academy. She has a companion named Airgetlam (Aihr-ah-geht-luhm) which assists her in battle. Millium is childlike, having the excitement and energy of a grade schooler. She is very energetic in every case, whether its for excitement or when she's scared. She can make remarks about the body shapes of females, so please keep that in mind. She also has practically no sense of personal space, and ends up frightening the male students a lot.

Millium has a childlike voice, and tends to be louder with her volume. She has a more melancholic yet energetic tone, and her non-battle quotes involve emotions with excitedness, nervousness, and sadness.