Operetta is a supporting character in the anime Weiß Survive, appearing as the middle sister of the Chaos sisters, a trio of opponents encountered inside the card battle space of the Weiß Schwarz trading card game. She is a teenage girl with purple eyes and gray hair worn in twin tails. The Chaos sisters are described as a group that together possesses every kind of appealing trait, with each sister covering a different set of personality types, and Operetta is characterized as the tsundere of the group.

In the story, the protagonist Takeshi faces the Chaos sisters during his early progress through the card battle world, making them one of his first major group of challengers. Operetta and her sisters act as antagonists in these matches, working together as a team. Their confrontation involves Takeshi using underhanded tactics, including a kick that allows him to look beneath their clothing, before he manages to defeat the three sisters using a combination of attack cards. This defeat marks the end of the sisters' role in the first series, though the Chaos sisters reappear in the sequel series Weiß Survive R, where they also show up in the real world.

Personality-wise, Operetta behaves as a classic tsundere. She acts as if she is interested in Takeshi, but she refuses to be straightforward about her feelings, playing up the part of a girl who cannot be honest. This behavior is presented as a deliberate strategy: the sisters use their charm to disorient and tempt their opponent during card battles, and Operetta's flirtatious yet prickly attitude serves as her contribution to that plan. Her motivation as a character is primarily tied to these battles, as she seeks to defeat the challenger by using her persona and card skills to gain the upper hand.

Her key relationships are with her sisters, the eldest sister Sies and the youngest sister Cal, with whom she operates as a unit. Toward Takeshi, her dynamic is adversarial but complicated by her feigned romantic interest, which she uses as a weapon in combat. In terms of abilities, Operetta is a capable card battler within the Weiß Schwarz battle space, fighting alongside her siblings, and her most notable trait is her ability to use her tsundere demeanor as a tactic to unsettle her opponents. Because the series is structured around short comedic encounters, her development is limited, and she functions mainly as a recurring comic opponent whose personality is defined by her role within the Chaos sisters and her teasing rivalry with Takeshi.