Raphtalia is the first real companion of the Shield Hero. Although she was originally bought as a slave, she was never treated badly and forged a strong bond with her master.

She later travels to another world and obtains the Vassal Katana, becoming the Katana Hero (刀の勇者 ). Additionally, she becomes the Heavenly Emperor of Q'ten Lo after overthrowing the previous emperor.
She has undergone some significant changes throughout the story. When Raphtalia is first introduced, she is a child with long, unmanaged hair and a dirty cloth gown. After being purchased by Naofumi, he gives her a haircut to an acceptable length, gives her a bath, and buys her a much more suitable set of clothes to adventure in. As a mixed-race of Raccoon and Tanuki, Raphtalia is shown to have fluffy dog-like ears and an averagely sized bushy tail.

After several weeks of traveling with Naofumi, Raphtalia's body inexplicably changes and she gains the appearance of a beautiful teenager or young adult. It is revealed that demi-humans grow in relation to the progression of their levels, which leads to Raphtalia's rapid development (though it is believed that she still has the mental maturity of a child, which is seen when she stares enviously at children playing with a ball).

During their travel to the Other World, L'Arc mentions to Naofumi that Raphtalia has reverted back to her Child-self when her level is been reset to one and she has to grind to reach her adulthood in that world before reuniting with Naofumi. In her adult form, Raphtalia begins to wear clothing much more fitting for a warrior, which consists of a hide breastplate, skirt, lace-up boots, and a pair of gloves. Raphtalia also switches from a small knife to a full-sized sword during this time.