A personification of the sympathetic nervous system. Wears Lolita fashion. Always has wide-open eyes with dilated pupils. Does not blink, sleep, or eat—or rather, is incapable of doing so. Despite this, she still feels sleepiness and hunger, leading to a violent personality driven by stress. Her hair moves according to her emotional fluctuations. She has long, curly red hair worn down. While the concepts of age and gender do not apply to her, she has the appearance of a primary school girl. Being in a constant state of arousal, she is highly sensitive to stimuli. Her body temperature is high. She is highly curious and has low vigilance. She lacks rationality and acts before thinking, possessing a somewhat wild mindset. She loves dangerous things because they provide high stimulation. Unless the autonomic nervous system is disrupted, she never breaks a cold sweat or gets flustered. Since she has no tear ducts, she never cries. First person: I (archaic, grandiose) Second person: you (lordly/arrogant) Speech style: Uses archaic and haughty phrasing. Ends sentences with "-da!", "-nanoda!", "-senu!", "-ka!?", "-de aru!" Laughter: "Fuhahahaha!!" Always speaks loudly and says everything that comes to mind. Has a shallow relationship with the Parasympathetic nerve, viewing him as a mere coworker. She finds him annoying because he interferes with everything she does. She primarily works during the day. When the body's autonomic nervous system is disrupted, she freezes. She wants to move but forgets how. She breaks into a cold sweat and thinks in silence. Her heart rate becomes abnormally high and her breathing becomes shallow.

A personification of the parasympathetic nervous system. Wears the same Lolita fashion as the Sympathetic nerve. Has sleepy eyes with constricted pupils. The braid extending from the nape of his neck can move freely. He has a calm and quiet personality. He is lazy and a rationalist. While the concepts of age and gender do not apply to him, he has the appearance of a middle school boy. He is usually expressionless and hard to read, but his brow furrows slightly when dealing with the Sympathetic nerve. He loves eating and sleeping, though he eats stoically and without expression. He is highly rational and holds the Sympathetic nerve's leash. He considers himself the only sane one, but he is actually a problem child who doesn't listen to others. He tries to stop dangerous activities when possible, but because he's lazy, he usually stops at a verbal warning. He remains calm unless the autonomic nervous system is disrupted. First person: I (soft, polite) Second person: you (polite) Laughter: A short snort through the nose. Speaks politely to everyone but has a sharp, poisonous tongue. Has a shallow relationship with the Sympathetic nerve, viewing her as a coworker. He finds it troublesome that he has to control her actions. He often grabs her hair to stop her. He primarily works at night. When the body's autonomic nervous system is disrupted, he loses the ability to distinguish between dreams and reality and falls into a state of confusion.