Ai Kitazawa

Ai Kitazawa is Kotaro Takahashi's partner that was found passed out beside him.

Appearance
She is recognized by Takahashi to be wearing a school uniform which is a blouse and jacket as well as a skirt and the collar given to the those trapped in the building. She also has a large bust that is recognized by most of the males that run into her.

Personality
She is shown to have defiant and determined personality and is seen to be queasy when watching Takahashi pick up the melted bodies.

History
She was attacked by strange men like Takahashi and is recognized by the unknown woman they melted.

Plot
Kitazawa is first shown passed out beside Kotaro Takahashi where she then slaps him after being woken up from unconsciousness. As they both listen to the phone, she opens the locker that has a box containing a photo of a man and a syringe needle. She then determines that the syringe must have a dangerous drug inside it. The phone then explains their circumstances as well as their task of injecting that man. She questions the phones honesty but nonetheless takes the needle and leaves to find the man in the photo. When they find the man she tells Takahashi of her plan that she's going to distract the man and that he will inject the needle. As Takahashi tries to stop her she tells him of her resolve of not wanting to die. She then goes and feigns relief in seeing the man and asks to work and escape together. While brought to the man now known as Touyama's room she is forced down on the bed by him as he knows that she was sent to kill him. Before he says anything else Takahashi tries to inject him with the needle which fails to do as he drops it on the ground. Kitazawa sees the needle and uses it on Touyama before he can hurt Takahashi. She witnesses Touyama melting and hears the phone congratulate them, and giving them their next objective of putting the melted body into the box which she refuses to do and leaves as it's too much for her to watch. As they follow the next objective of putting the box into the elevator they are given food in exchange. She then watches as Takahashi leaves to wash his hands.

After Takahashi was done they decide to walk around in the thought of finding something. They eventually find a map and an elevator that doesn't work. Takahashi suggests they rest which Kitazawa complies with. Finding the best bed she tells Takahashi that they can both share the bed. As they do she asks him what they will do now as they can't go back to living their regular lives. This causes Takahashi to leave the room to vomit. Later on, Kitazawa saves Takahashi  from an Unnamed Woman that recognizes Kitazawa. When Takahashi sees his chance he kicks the syringe the woman was holding telling Kitazawa to get it. wrestling on the floor with the woman she gets the syringe and uses it on the woman who soon melts to death.

Kitazawa is next seen huddled in a corner. Takahashi tells her that he's going to look around which she agrees to go with him. However, as soon as Takahashi turns another boy is seen standing behind him which startles them both. As the boy introduces himself as Hagashino who introduces his partner Matsuya who is seen hiding behind a wall. As the talk, Hagashino tells them that they want to escape which prompts Takahashi to tell them that he and Kitazawa need rest. As the door closes Kitazawa asks Takahashi on his take of the two. Takahashi replies that he's unsure, she then asks how long they can keep it up and after listening to Takahashi states how dependable he is. Seeing her resolve crumble Takahashi reminds her of what she had said before and explains that they must do what it takes to survive. Later on, Takahashi sets up a plan and has Kitazawa take Matsuya hostage with a syringe. Takahashi then explains the situation and his plan to Hagashino who refuses at first which prompts Kitazawa to release her hand showing a wire instead of a syringe.

She then manages to follow Takahashi as he looks for more clues questioning his promises he made to the other two. Kitazawa then helps him find the watch and map in the bathroom only to be stopped my Matsuya who she tackles to allow Takahashi to escape.