Midori Sugiura is a key character in the anime My-HiME. She is a woman in her mid-twenties who insists she is seventeen, a claim that no one around her takes seriously. She initially works as a waitress at the Linden Baum diner alongside the protagonist, Mai Tokiha, where her clumsiness often leads to broken dishes. Later, after a bus accident leaves Mai’s homeroom teacher hospitalized, Midori chooses to stay at Fuuka Academy and becomes the substitute and eventually the official homeroom teacher for Mai’s class, instructing Japanese history. Her genuine passion for history and archaeology is a defining trait; she becomes ecstatic when discovering historical artifacts or documents, and this enthusiasm often drives her actions.

Beneath her outwardly goofy and energetic personality, Midori is the oldest and most experienced of the HiME, a group of girls who can materialize photon-based weapons and summon powerful creatures called Children. She often acts like a self-proclaimed fighter of justice and takes on a leader-like role, rallying the other HiME to form a collective group she dubs the HiME Sentai. Though her leadership style can appear arrogant and clumsy at first, she proves to be highly intelligent, resourceful, and genuinely dedicated to protecting the other HiME. She actively tries to discourage them from fighting one another when the true nature of the HiME festival is revealed, showing her protective and selfless side.

Midori’s motivations stem from her research into the history of the HiME, which gives her deep insight into the cycles of conflict and sacrifice. She is determined to stop the festival’s destructive conclusion and seeks a way to end it permanently. Her investigative nature leads her to uncover that the school chairman, Mashiro Kazahana, is an imposter and that the real Mashiro died years ago. After confronting Mashiro and learning the truth, she is given the means to halt the festival. She ventures into a secret chamber beneath the mansion to activate an android, Miyu, hoping that Miyu’s loyalty to Alyssa Searrs will provide the key to defeating the Obsidian Lord. During this mission, she sacrifices her Child, Gakutenou, to protect the android from Mikoto Minagi, sustaining severe injuries in the process.

Key relationships shape her journey. Her closest friend is the school nurse, Yohko Sagisawa, who has known her since their college days. Their friendship is marked by frequent drinking sessions, with Yohko often being the heavier drinker. Midori’s most important person, the one whose life is tied to her HiME status, is her former college professor, an older man for whom she has strong romantic feelings. Yohko is occasionally taken aback by Midori’s attraction to a man much older than her, but this bond remains central to Midori’s emotional anchor. At the end of the series, Midori recovers and embarks on global adventures with her professor, retrieving ancient artifacts in an Indiana Jones–style life, though a comedic extended ending shows her back at the diner, much to the surprise of her former coworkers.

In terms of abilities, Midori is a HiME whose element is a labrys, a large double-headed axe. She wields it with considerable skill, often displaying it dramatically but also using it effectively in combat. Her Child is Gakutenou, a creature resembling a cross between an armadillo and a lion. Its hind legs transform into wheels, allowing it to move at high speeds on land and in the air. It possesses an extendable blade on its head that can cut through solid rock and can generate tornadoes by spinning its wheels at high power. Rocket thrusters on its back enable a powerful spiral dash attack that can pierce through stone or metal. These combat capabilities, combined with Midori’s tactical knowledge and years of experience, make her one of the more formidable HiME, even if she often downplays her seriousness behind a cheerful and reckless facade.