Rena Asteria is one of the central characters in the anime series "Regalia: The Three Sacred Stars." She is portrayed as a mysterious and powerful girl with a deep connection to the Regalia units, mecha that play a pivotal role in the series. Rena is characterized by her calm demeanor and unwavering determination. Her relationship with the sisters, Yui and Rena, is central to the storyline, as they uncover secrets about their past and confront various threats. Rena's character is crucial in driving the plot forward and exploring themes of friendship and identity.