Chika Sawada is the older twin sister of Chiaki Sawada. Both sisters attend the Kouka School of Musical and Theatrical Arts as preparatory students, united by their ambition to perform musume-yaku roles. This shared dream ignited after witnessing a Kouka Revue performance featuring twin bunny ladies, prompting them to audition together.

Chika passed the entrance exam on her first attempt during her initial high school year. When Chiaki failed that same year, Chika chose to delay her own enrollment. She retook the exam the following year to enter Kouka alongside her sister. This sacrifice placed significant strain on their relationship, forcing Chiaki to confront the weight of Chika's choice.

Personality-wise, Chika projects a steady and cheerful exterior. She habitually prioritizes her sister's well-being over her own ambitions, often stepping back during critical moments. This self-effacing tendency fosters underlying bitterness, intensified by Chika's private conviction that Chiaki possesses greater innate talent. She channels this envy into personal drive and ambition.

The twins' relationship evolves from this initial tension. Chika's pattern of sacrifice and Chiaki's resulting guilt created a dynamic that hindered communication. Over time, both sisters actively work to acknowledge this imbalance, focusing their efforts on establishing healthier terms for their bond. They strive for mutual support free from resentment or excessive dependency.

Chika's name combines the kanji for "thousand" (千) and "summer" (夏). Their shared surname, Sawada, merges "marsh" (沢) and "field" (田).