Akane Shida is the youngest Shida sister and Aoi Shida's twin. She is a first-year middle school student with a delicate, slender frame standing 4'9" tall and possessing less developed breasts than her eldest sister. Gentle wavy black hair styled in long hip-length twintails, glasses, and relatively droopy eyes contribute to her intelligent, frigid, and shrewd appearance. Her voice has a limited tone, conveying pragmatism.

Despite being twins, Akane exhibits frigidity and shrewdness contrasting sharply with Aoi's warmth and restraint. Her outstanding intellect makes conversing with peers difficult. She demonstrates great composure and rationality, making her an ideal source for advice, yet struggles socially in settings with many strangers, displaying tendencies described as almost autistic. Academically excellent, particularly in mathematics, she obtained the Suken 1st-kyu certification while a sixth-year elementary student.

Akane shares a significant relationship with Sueharu Maru, whom she calls "Haru Nii." Due to her intelligence and rationality, Sueharu relies on her more than her sisters, frequently seeking advice, though her manner of speaking hinders communication. Like her sisters, Akane harbors romantic feelings for Sueharu. Within her family, eldest sister Kuroha Shida is very supportive and spoils Akane when she feels insecure. Aoi helps Akane navigate school social situations, as Akane finds befriending other children challenging. Akane inherited her concentration from her father, Michikane Shida, but also his difficulty with social interaction.

Following the Confession Festival incident, Akane and her sisters noticed Kuroha acting strangely. Akane and Midori visited Sueharu to inform him that Kuroha appeared to have lost her memory, demonstrating Akane's attentiveness to family matters.