TV-Series
Description
Hikari Myōdō is Akina Myōdō's younger sister, burdened by a chronically weak constitution leading to frequent hospitalizations. This condition originates from ten years ago when the otherworldly entity Sybilt parasitized her body, draining her life force and causing progressive physical deterioration, including a smaller stature than her peers. Her resulting dependency necessitates Akina's daily care.

Despite her health struggles, Hikari generally exhibits a cheerful, excitable, and playful demeanor. She frequently teases Akina, reflecting their close bond. Yet this outward positivity masks profound guilt tied to the childhood accident that caused her condition: during a mountain camping trip a decade prior, she wandered off and became trapped in a cave-in. Though Nao Inabe ultimately rescued her, the incident allowed Sybilt to latch on. Hikari internalizes blame, believing her illness forced Akina to sacrifice his childhood, dreams, and aspirations solely to care for her. She perceives him becoming emotionally hollow, fueling deep-seated remorse.

A turning point arrives when Sybilt, after Akina wins the Fated Clash, approaches her. Sybilt offers Hikari the chance to become an owner of a Destined One card—specifically the Destined One of Time, Liael゠Odium—promising her wish to travel back and prevent the accident could be granted if she wins the Destined Showdown. Under Sybilt's mental suggestion, Hikari accepts and joins the tournament to fight against Akina and the others. Her core motivation is to erase the accident, freeing Akina from her burden so he can reclaim his life. She actively avoids Akina at home during this period, reflecting her internal conflict and determination.

During her Destined Showdown fight against Akina, Hikari reveals her true feelings. She declares herself the "sinner" responsible for his suffering, criticizes his self-destructive selflessness, and asserts changing the past is the only way to restore his sense of self. Utilizing Liael Odium's Divine Skill, which manipulates time to grant her an extra turn, she defeats Akina and volunteers to represent the Destined One owners in the tiebreaker round.

This leads to a confrontation with her future self, revealed as the Seventh Fated One. Future Hikari challenges Present Hikari's motivations, arguing the desire to change the past is fundamentally selfish and disregards Akina's own choices and feelings—specifically, that caring for her brought him genuine joy and purpose, including his connection to Vanguard. Present Hikari reacts with hostility, dismissing Future Hikari as a hypocrite and unleashing her Divine Skill. Despite this advantage, Future Hikari wins, breaking Sybilt's mental corruption. This defeat forces Present Hikari to confront her flawed perspective. She reconciles with Akina, acknowledging his agency, and they mutually agree to support each other.

Following Sybilt's defeat and the revelation of its role in her illness, Akina's wish during the Fated Clash cured Present Hikari by expelling Sybilt from her body in the current timeline. However, Future Hikari's timeline diverges because Akina's wish remained unfulfilled there, leaving Sybilt embedded and causing her ongoing sickness. Future Hikari's actions, driven by a similar desire to save Akina, were instrumental in setting the Destined Showdown events in motion. Further backstory confirms Nao Inabe saved Hikari during the original cave-in accident.

Physically, Hikari has shoulder-length hair that is mostly dark blue with a distinctive streaked section above her forehead featuring red at the bottom fading to white at the top. Her typical home attire includes a blue brooch, a yellow dress with a white lapel and puffy sleeves, grey socks, and black ballet shoes.