Kotori has the ability to switch with other people and things as well as allowing others to come with her when she uses her powers. However she can only use her powers once which then causes her to hang up. Despite this handicap, her ability has often come into place in vital situations. She is not familiar with other magicians when still lived in the lab.
Kotori is a clumsy but soft-hearted girl. She gets nervous easily, and when that happens, she will start to stutter. She likes all kinds of desserts and does eat a lot of food.
It was later revealed that Kotori was a special host found by Chisato to contain a special drasill called "Grane", which has the ability to destroy all other livings on earth if fully hatched. That is why both the lab and Hexenjagd (witch hunter) were looking for her. Since Grane contains the memory of Chisato's little sister: Rena, Chisato decided to "revive" Rena and let Grane fully hatched. He and Valkyria strike the observatory and kidnap Kotori.
When Murakami and Kuroha found Kotori, and was nearly killed by Valkyria, Kotori showed the true power of Grane and neutralized all magic from Valkyria. However, Grane was also hatched at the same time and sending out light curtain that will dissolve all livings if touched earth. Kotori begged Murakami to eject her Harnest so she wouldn't kill the others, Murakami painfully fulfilled her wish. She became the first main character to die in the series.
After Kotori was ejected, she seemed to recover the memory of Rena and expressed her anger to Chisato in Rena's persona. Whether or not she has Rena's conscious from the beginning remains unanswered.