Erica

Erica is Kilala's best friend and a model student in her school. Erika is very friendly, cute, and kind, she is very much like a princess. After she is crowned princess at the 'Princess Contest', she is kidnapped by two cloaked men (later revealed to be humanoids) and it is up to Kilala and her newfound companions to retrieve her. Soon after Kilala and Rei's adventure in Snow White's world, the duo find Erica, but she's behaving quite abnormally and even tries to steal the tiara of the seventh princess because the men hypnotized Erica to steal the tiara for them.

(Source: Wikipedia)