Age: 24 (claims 17)
DOB: April 6
Height: 157 cm
Weight: 45 kg (99 lbs)
Blood type: B
Midori first appears as one of Mai's co-workers at the Linden Baum diner. She claims to be 17 years of age, even though she is really 24, and no one believes her. She is friends with school nurse Yohko Sagisawa from their college days and she eventually becomes a teacher at Fuka Academy. A DVD special reveals that Yohko met Midori on the first day of college when Midori sat down and started chatting amiably. Yohko suggests that Midori has a "thing" for older men.
Midori is revealed fairly early in the plot to be one of the HiMEs after trying to find documents related to the HiME festival at Shiho Munakata's shrine. She is a well known history buff and is in ecstasy after being accidentally locked in the shrine storeroom and discovering it to be full of historical material. When Mai Tokiha finds her in the storeroom they accidentally remove a seal that unleashes an Orphan, which Midori defeats with ease by herself after seeing how reluctant Natsuki, Mai and Mikoto were with working together. She then establishes herself as the new history/homeroom teacher in Mai's class.
When SEARRS invades the academy, she helps to unite the HiMEs and proves helpful in destroying the army forces surrounding the school by the bay. After the defeat of Alyssa Searrs and Miyu Greer, she bands all the known HiMEs together to form a collective group whose goal is to work together to stop Orphans (while slyly indicating that they will be doing most of the work while she works on her research). She dubs them the HiME Sentai (Task Force), much to the displeasure of Natsuki Kuga and Nao Yuuki. After convincing all the HiMEs to partake in the new group, she takes them all to celebrate by having all go through a wild night of karaoke and partying.
Though she appears to be goofy and more of a gung-ho justice fighter than a serious leader, she is actually the most experienced HiME, being the eldest of the group, and reveals herself to be a more than capable leader and far more intelligent than she lets on. She can act maturely when she wants to and actually takes it upon herself to protect the other HiMEs, who she considers entrusted to her and therefore under her guidance. When the competition between the HiME is announced she actively tries to discourage the other HiMEs from fighting. She also appears to have known the course the battles would take, possibly through her research. She is shown to have major background info on the legendary HiME cycles, and gathers more and more information as time passes.
She eventually finds out that the school chairman, Mashiro Kazahana, is an imposter, and that the true Mashiro died years ago. After initially confronting Mashiro and Fumi, she learns from them the truth behind the Festival of the HiMEs, and is given the means to stop the Festival from going on ever again. After tying up loose ends and leaving her thesis and research to Yohko, she sets off to Mashiro's empty mansion to execute her plans.
At this point, the other HiMEs have all but turned on each other, and Midori is shown to be the one person who seeks to stop the Festival at all costs. Going into a secret room underneath the mansion, she enters a sealed room using the special key Mashiro gave her, and is confronted by Mikoto Minagi, who has been given orders by the Obsidian Lord (who is possessing Reito Kanzaki) to stop Midori. Midori manages to initiate the start-up for the android held in stasis, apparently the only person capable of stopping the festival and the Obsidian Lord; this costs her Child by Mikoto's hand as she uses Gakutenou to stop a hit meant for the android from Mikoto's Child. Her efforts prove successful, as the android, revealed to be Miyu Greer, manages to escape fully functional, and with all her prior memories intact. Midori did not reboot Miyu's memories, hoping that the dedication that Miyu had for Alyssa would prove to be helpful. She is injured severely after her fight with Mikoto, and is taken by Mai to Yohko, where she remains in critical care for some time.
Her most important person was her Professor, an older man who was a colleague of hers while in college. Yohko is usually put off by the fact that Midori is attracted to a man so much older than her, since the Professor is shown to be in his mid fifties at least. At the end of the series she is shown traveling the world with her professor rescuing ancient artifacts, Indiana Jones style.
Element and Child
The My-HiME version of Midori has a labrys as her Element, which she has a habit of using for show more often, parading it around as a symbol rather than fighting with it. However, she demonstrates it is not merely for decoration as she shows herself to be very proficient in handling it. It has shown to have boomerang properties. Her Child is named Gakutenou (愕天王), a strange armadillo/lion creature, whose back legs transform into wheels, allowing the rider to move at high speeds on land and in the air. It has an extendable blade on its head that can cut through solid rock, and by rotating its wheel at high power, it can launch a tornado that can trap an enemy within. Its shape allows it to become a living projectile; the rocket thrusters on its back give it an incredible amount of thrust, which it uses in its Spiral Dash attack: gathering speed, it rushes forward, covering itself in energy and then physically blasting through whatever is in its path. It can go through a wall of solid stone and even the metal hull of a ship.
In the My-HiME manga, Gakutenou does not retain any of its anime abilities; instead, it morphs into a giant mecha, using its sheer strength and energy weapons to fight with.