- Kanna was born in 1997 to Kiriko Endo. One day, Kiriko returned back to the home of her mother and younger brother, Kenji Endo, begging them to take in Kanna for her. Kenji agreed and raised Kanna in her childhood years
- While she was a baby, her grandmother, and the young employee of the supermarket, Erika, were in the convenience store when suddenly members from Friend's organization broke into the store desperately trying to kidnap Kanna. Kenji arrives and saves Kanna from them just in time, but the convenience store is then burned down by Friend's henchmen.
- On December 31st, 2000, Kenji allegedly "died" during the Bloody New Year's Eve and she was taken in by Yukiji Setoguchi, a close friend of Kenji's.
As a seventeen year old high school student, Kanna worked for Chinese restaurant, Kyoko, often getting herself involved with issues between the Chinese and Thai mafias. Also she was a great fan of Seven Dragon's Ramen (the owner is the last disciple of the original ramen she ate with her uncle, when she was a child).
In the third year of the Friend Era, coupled with her charisma, Kanna makes an able leader, leading a rebel faction against Friend under the moniker of "Ice Queen" (冰の女王 Koori no Joō?)
Kanna seems to possess supernatural abilities such as ESP. How she obtained such powers is unknown, though it is hinted by Friend to be the result of a secret medicine given to her mother before childbirth.
Kanna's facial features vaguely resemble those of Anna Liebert in Urasawa's preceding manga Monster. Both are also well-liked among the social groups they choose to be associated with and have been born with some degree of experimentation on them. Also like Anna, who chases after Johan in order to stop him from killing more people, Kanna chases after Friend in order to bring down his dominance over the world.