Erena Amamiya shines as a third-year middle school student in Mihoshi Town, celebrated as "The Sun of Mihoshi Town" for her bright personality and athleticism. Her family runs the flower shop "Sonrisa" – Spanish for "smile" – reflecting her Mexican heritage through her father. She helps at the shop and cares for her five younger brothers when her parents are busy.

Her civilian look features tan brown skin, curved purple eyes, and thick golden hair reaching her chest, often held by an orange headband with small braids behind each ear. A beauty mark sits beneath her left eye. Typical attire includes an off-white, midriff-tied top with orange designs, denim shorts, a purple choker, and burnt orange sneakers. In winter, she layers a white sweater over an orange shirt with blue jeans, sometimes adding a brown jacket and dark orange scarf.

Using the Star Color Pendant and Star Color Pen, she transforms into Cure Soleil, the Pretty Cure of the Sun. Her Cure form boasts bright blonde hair in a thigh-length ponytail, accented by purple headbands with star decorations and a beaded tiara. An orange and yellow Cure dress features a star-patterned belt, a pouch for her pens, and light yellow boots with star motifs. Her transformation call is "Light up the sky! A sparkle full of emotion! Cure Soleil!" Her primary attack, "Soleil Shoot," purifies enemies by channeling solar energy through her pendant and pen.

Warm, approachable, and responsible, Erena often mediates conflicts among friends and siblings. Childhood insecurities about her skin tone once caused social isolation, but embracing her uniqueness strengthened her self-acceptance. She believes protecting others' smiles fuels her strength. Initially prioritizing family duties, she later pursued her dream of becoming a translator like her mother, balancing both.

Key relationships include a respectful rivalry with Tenjo, an antagonist initially opposed to interspecies bonds. After learning of Tenjo's traumatic past, Erena helps redeem her, bridging their differences. She shares a supportive friendship with classmate and fellow Mihoshi Middle School "idol," Madoka Kaguya (Cure Selene), valuing Madoka's many talents.

Her journey as a Pretty Cure began witnessing the cosmic fairy Fuwa under attack. Overcoming fear, she defended Fuwa, declaring her resolve to protect others' happiness. This awakened her Cure powers. Her narrative emphasizes diversity and representation as the franchise's first prominently dark-skinned Cure, intentionally designed by director Hiroaki Miyamoto to reflect Mexico's cultural vibrancy and challenge monolithic Japanese beauty standards.

The series epilogue shows her future as a television interpreter covering space events, supporting teammate Hikaru's astronautic endeavors.