Stella Vermillion is an A-rank Apprentice Knight and princess of the Vermillion Kingdom. She is a young girl with long vermilion hair tied in twintails and crimson eyes, average height and has large breasts and a voluptuous figure.
Stella initially appears to be feisty, hot-blooded, and quick to anger possibly due to her sheltered upbringing. However, later she is shown to be anything but bitter, and is even willing to admit her mistakes and be friendly with others. Despite this, she exhibits frequent bouts of jealousy especially when it comes to Ikki.
(Source: Rakudai Kishi no Cavalry Wikia, edited)