Nagisa Sagan (目渚 Sagan Nagisa) is an easily angered woman who conducts experiments, and creates humans who cannot feel physical pain known as Zeros. It is later revealed that despite her young appearance, Nagisa is over 30 years old. Little is known about her background; It is known she had a sister, but what has become of her sister has not yet been confirmed. She created Youji Sagan in her younger sister's image, perhaps as an attempt of remembrance or to erase a pain in her heart, but reasons are still unknown. Her over-the-top behavior and strange lifestyle leaves her alone and alienated. She befriends 7, and shamefully confesses that she is her only friend.