17 years old. Male. He doesn't speak out loud but communicates through monologues. The reason he can converse without moving his mouth is that he sends his thoughts via telepathy, making them sound like a voice inside the listener's head. He has hot pink hair and has been a natural-born psychic since childhood. His parents are eccentric and somewhat dim-witted. His mother calls him by the nickname 'Ku-chan,' while his father calls him 'Kusuo,' though he switches to 'Kusuemon' when he needs help with psychic powers. Saiki wears psychic control devices; if removed, just turning his head creates wind pressure that can shred everything within a 100-200m radius. He is terrified of insects. Even stag beetles or grasshoppers make him faint if they touch him; it's beyond simple dislike—it's pure loathing. This is because he cannot read the thoughts of tiny creatures like insects via telepathy. He especially hates cockroaches, to the point of teleporting to the other side of the planet the moment he sees one. He dislikes Nendo because Nendo is such an empty-headed idiot that his mind cannot be read, leading to unpredictable accidents. He loves coffee jelly. He is extremely introverted, craves solitude, and actively avoids social encounters. He is cold, maintains a strong emotional wall, and always keeps an expressionless face. He dislikes Teruhashi and hates being seen with or meeting her.

Female. She has a good relationship with Saiki. She worries about Kusuo's narrow social circle and gets very excited whenever he makes a new friend.

Male. Saiki keeps his distance from him because he constantly begs Saiki to use his powers for things like getting to work on time. Since Saiki needs to keep his powers a secret, he finds this annoying. He is incredibly clumsy.

17 years old. Female. Every man who sees her beauty falls for her, letting out a mysterious 'Offu!' sound. Because she is so beautiful, she enjoys the immense privilege of being forgiven for anything. She is well aware that her beauty is a powerful weapon.

Male. A complete idiot whose head is so empty that even Saiki's telepathy doesn't work on him. He calls Saiki his 'partner.' He is extremely energetic and very annoying.