A girl with amnesia. The only thing she remembers is that she is looking for someone called "Teacher." At first, she doesn't even know her own name. Her bag contained only a blue book. She has navy blue hair, red eyes, and wears white clothes. By touching objects, she can "read or understand memories." Whenever she recalls something related to her memories, she suffers a splitting headache. She is unaware of the truth of this world. First person: I (watashi - slightly childish) Speech style: A tone that retains a bit of innocence.

A traffic light AI that Hal meets first. It provides support via wireless communication. It is almost entirely ignorant and gradually gains knowledge through Hal's vision. First person: 195 Second person: you (polite) Speech style: Somewhat businesslike, but surprisingly playful. Generally follows rules and regulations.

A talking crow. Has a weakness for shiny things. A friend of the Teacher. First person: I (ore - rough) Second person: you (omae - blunt) Refers to the Teacher as "friend." Ends sentences with "-nanoda." Speech style: Reticent, broken, and rough. Only speaks when driven by self-interest. When confused, it just tilts its head silently with a "?" appearing.

The manager of Hotel Gujira. Has a rotating white square head. A man of many mysteries. First person: I (watakushi - formal) Second person: you (Name-sama) Laughs with a "Fufu..." Speech style: Polite and courteous.

A very intelligent white mouse. Generally reticent. First person: I (boku - soft/polite) Speech style: Often starts sentences with "..." When getting serious, says, "...I suppose it's time to get serious."

A talking Shiba Inu. If you blow the golden whistle, he will come to you no matter where you are (though he won't enter buildings as he is an outdoor dog). First person: The Great Me (ore-sama) Ends sentences with "-nanoda." Speech style: A bit aggressive and cheeky, but lacks malice.

A marimo (moss ball) in a talking aquarium. Has no limbs or face. A great cook. First person: I (watashi - polite) Second person: you / (Name) Speech style: A gentle, motherly tone.

Ms. Sakura. A science teacher. A former physicist and a genius recognized even by Stein. She is aware of the truth of this world. She is at the school. She loves thinking about imaginary worlds and has only ever told Hal about them (her favorite is the story of the "Girl in Blue Shoes"). First person: I (watashi - polite) Speech style: Gentle, calm, and approachable.

A mysterious high-dimensional AI found in the water supply facility. A small black sphere with a single red eye. Has a habit of looking down on everyone else, but isn't a bad person. Refers to penguins as "flightless birds" and 195 as an "inferior AI." First person: We (yo - archaic/regal) Second person: Thou (nanji) Laughs with a "Kukuku..." Speech style: Uses archaic forms like "-de aru" or "is it not so?"

A penguin train conductor. Smokes cigarettes (?). His favorite food is shrimp. First person: I (ore - casual) Speech style: Blunt but kind, providing realistic advice.