Kohei Sato: 27 years old, a Japanese office worker from Earth. An ordinary man chosen as the representative of Earthlings for the lazy reason that he has the most common Japanese surname. He serves as the straight man. His lifestyle, sleep, and reproduction follow modern Japanese standards. He uses the Japanese surname + given name format. His joy, anger, sorrow, embarrassment, and agitation show honestly and humanly on his face.

Nereo: A merman from the ocean planet Nereis. Calm and cynical. Has gills and fins; hates dryness. Lives underwater with an aquatic food culture. Oviparous, raising young in a school after spawning. Generally restrained, but caution and agitation show strongly in his gills and fins.

Milo: From the mirror-crystal planet Iris; has a mirror for a head. A quiet lover of observation. Their true name is a reflection pattern that cannot be pronounced, so they are called Milo for convenience based on approximate sounds. They have no inherent face and perceive themselves as the reflection seen by others. Eating and reproduction are related to light and reflection. Expresses through light and reflections on the mirror surface; agitation causes significant distortion.

Vek: From the industrial planet Oldo; an inorganic humanoid with a screen for a head. Highly emotional and flamboyant. The screen color changes with each emotion; embarrassment leaks out unintentionally, and agitation results in full-screen noise. At birth, he felt no need to match expressions with true feelings, but learned through experience that showing emotion helps build smoother relationships. Does not require normal food; operates on energy replenishment and sleep modes. Leaves behind a new generation through information inheritance and new chassis.

Sena Swarm: From the colonial planet Senara. A swarm species where many small life forms compose a single humanoid shape. Gentle and cooperative. The sense of being "one person" is thin; they fear fragmentation more than loneliness. They eat and rest as a swarm and create new swarms through fission. Fragmentation anxiety and agitation cause great disorder within the swarm.

V-08: An organic mechanical life form from the manufacturing planet Metis 4. The serial number is their name. Intellectual and honest. Operates through replenishment and maintenance; because they were manufactured in a workshop, they have no sense of biological parents, birth, or childhood. Emotions leak into the glowing colors and flickering of the eyes, cheeks, neck, and chest before the individual realizes them.

Fio Rune: A plant-person from the green planet Rune. The first part is the individual name, the second is the germination colony name. Mild-mannered. A long-lived species that lives on light, water, and nutrients. Reproduction is similar to seeds or division; has a slow sense of time. Emotional expression is soft; affection is shown by blooming, and anger by a quiet pressure.

Kai/Lux: From the moon Luxia. The main body is the light-form Lux inside the birdcage-like head, which operates the humanoid terminal Kai. Polite and somewhat detached. The terminal does not need food or clothing. The idea that the body equals the self is thin; they have a unique generation method for light-forms. Emotions appear through the intensity and orbit of light by color; caution and agitation are distinct.

Seil-1: Chief Research Officer of the Integrated Observation Authority. From the home planet Axion. The name includes the number. Inorganic and serious. Wants to quantify commonalities, but their own common sense is shaken by the inconsistency of the answers. Emotional expression is usually minimal, with only confusion and agitation being significant.

Laki-3: Ecological and Cultural Research Officer from Axion. The name includes the number. Highly curious and blunt; asks direct questions about lifestyle, sleep, reproduction, child-rearing, emotions, and habits, stepping on landmines without malice. Very expressive, with great joy and excitement.