Sena Hoshimiya is Eiji Hoshimiya's younger stepsister, their bond formed when their divorced parents remarried. As a child, a decade before the main events, she met the wish-granting entity Daisy and wished for her mother, father, Eiji, and herself to "be together forever." This wish unintentionally caused the Great Destruction, a catastrophic event causing widespread devastation and death, including Rin Kurenai's parents. Sena suffered severe leg injuries in this event, confining her permanently to a wheelchair and requiring continuous medical treatment and rehabilitation at Hoshimiya General Hospital under her uncle's care. Sena possesses a youthful, petite appearance with green eyes and long brown hair typically cut to shoulder length. She consistently wears a white pediatric hospital gown, marking her as a long-term patient. Beyond her leg injuries, she suffers from a severe, incurable blood disease; medical assessments at the story's start gave her approximately six months to live. To halt her illness's progression, Abraham Louis Fran used his "Chronographic Caliber" Order to place her inside a time-stasis container. Outwardly cheerful, optimistic, and deeply affectionate towards Eiji, Sena cherishes her brother. She marks her calendars with symbols denoting positive days, like Eiji's hospital visits. However, beneath this innocent facade lies a complex, calculating personality. In high-stakes situations—such as her kidnapping by her stepfather (Eiji's biological father) Gennai Hoshimiya—she displays surprising calm and guile, strategically processing information to aid Eiji. Darker traits emerge, like threatening death over a trivial dice game loss, revealing a ruthlessness belying her fragile appearance. This manipulative side earns her the moniker "The Fake Cutie." Sena's role intensifies when Rin Kurenai targets and kidnaps her, stabbing her through the chest to lure Eiji into confrontation. Eiji rescues her by forcing Rin to heal the injury using his Order. Later, Fran uses her as a hostage to coerce Eiji's cooperation with the Dazaifu Central Bureau. The truth about her past surfaces: her wish caused the Great Destruction, and her original Order, "Bind Dominator"—granting domain-based control over people and objects—was unknowingly stolen by Eiji using his true power, "Illegal Digger," which usurps others' Orders and memories. This theft happened because Eiji's childhood wish was to "take Sena's fault" upon himself, absolving her blame for the catastrophe but altering his own memories. Following these revelations, Sena's character shifts significantly. Kidnapped by Gennai, who intends to sacrifice her to open a "Gate" to a new world and trigger another Great Destruction, she displays hidden depths, calmly assessing her situation and manipulating information to assist Eiji. Presumed dead after Gennai's plan fails, she later resurfaces alive with a transformed personality and motives. No longer the innocent victim, she becomes antagonistic, actively creating new Orders and seeking further destruction, prompting Rin to target her for death in retaliation for the first Great Destruction. Her relationship with Eiji strains due to her actions and altered demeanor, though he remains determined to save her.