OVA
Description
Setsuna Kiyoura operates as the central antagonist Doctor S in the "Magical Heart Kokoro-chan" special, unleashing a virus with assistant Tanaka that transforms Sakakino City's citizens into perverted zombies. Her philosophy as Doctor S asserts that evil validates heroes and heroes necessitate evil, directly challenging heroes like Magical Heart and Magical Word.

Beyond this role, she attends Sakakino High School as the impassive, taciturn class representative of Class 1-3 alongside Sekai Saionji and Makoto Itou. Her childhood bond with Sekai persists despite distancing from mutual friend Niki Ookuma. Setsuna displays fierce protectiveness toward Sekai, strategically manipulating Makoto's romantic life to secure Sekai's happiness, including obstructing interactions between Makoto and Kotonoha Katsura.

Petite and frequently mistaken for a junior high student, Setsuna is the shortest main character. Past bullying over her height fuels self-consciousness about her underdeveloped physique compared to peers like Kotonoha and Sekai. She typically wears her school uniform and ties her medium-length dark green hair with a ribbon.

In broader series lore, Setsuna is the daughter of Mai Kiyoura and Shun Hazama—explicitly aware Shun is her father, unlike her half-sisters. Her complex family ties include Sekai Saionji as a paternal half-sister. She fell for Makoto after he defended her from bullies during their entrance ceremony and encouraged her class representative role. Despite her feelings, she exchanged seats to advance Sekai's romance with Makoto.

Her visual novel arc features an impending transfer to Paris, driving her to intensify efforts to bind Makoto to Sekai. This culminates in her sleeping with Makoto to reinforce his commitment—a failed gambit. Alternate routes show unexplained transfers, her remaining in Japan, or pregnancy with Makoto's child, leading to declarations of being "his wife" to his mother.

In spin-offs "Summer Days" and "Shiny Days," Setsuna gains prominence. She temporarily works at Radish restaurant when Sekai contracts mumps, interacting with Makoto. These narratives expose heightened emotionality beneath her stoicism, linked to childhood trauma from a friend's fatal illness. Subtle smirks or V-signs occasionally surface after personal victories or provocations.