Age: Unknown
Classification: Esper
Affiliation: ITEM (De facto leader)
Ability: Meltdowner
Level: 5
Mugino is one of Academy City's Level 5 espers. She is ranked #4th and has the ability "Meltdowner". She can retain "pure" form of electrons (fix them in an ambiguous state which is neither a particle or a wave, and manipulate them into a beam which can melt down pretty much anything. She is also the leader of ITEM, the underground peace-making organization.
Mugino's appearance may suggest she's gentle and kind, but in reality she's a sadistic, battle-hungry fighter who looks down on all she deems weaker. She shows a compassionate face towards her teammates, although she would dispose them if they interfered in her way.
She encounters Kakine Teitoku, leader of SCHOOL in the war of Acadmey City's underground organizations, but was defeated. Shortly after she kills her subordinate in ITEM, Frenda for betraying the organisation. And around the end of the war, she makes a decision regarding Takitsubo Rikou, which led to her fighting against Hamazura Shiage, a level 0 who was an underling of ITEM. Surprisingly Hamazura wins the fight with a combination of luck and brains. Mugino was severly damaged in the fight, losing an eye and an arm, which led Hamazura into believing her to be dead.
But later she reappears in Russia, having acquires a replacement arm and a monocle that snugly fits in her right eye socket. After losing her arm every encounter that she had with Hamazura left Mugino more and more imbalanced, she developed a huge obsession with getting rid of Hamazura. She becomes obesessed to the point of abusing Body Crystal to defeat Shiage. By the end of volume 22 she finally decides to make peace with herself and with Shiage, finally returned to being the "old Mugino" who trusted her teammates and friends.
In To Aru Majutsu no Index: New Testament, Mugino has had her eye replaced with a mechanical one and covers up the rest of her injuries with makeup and has gotten a prosthetic arm that she is able to use as well as a real one. These replacement body parts make it look almost exactly the same as how she used to look before she fought Hamazura. She has also rekindled relations with the rest of ITEM and is shown to regret having killed Frenda.
Also Mugino's personality is shown to have changed greatly in New Testament. She is far kinder than she was in the first series and shows far less bloodlust and obsession than the times during the conflicts between underground organizations. She is also shown to think more of lower level espers and no longer look down on them as much as she used to.
