— Saiki kusuo. ⁰¹

Kusuo Saiki is a 16-year-old teenager of average height and slender build. He has short, neat, bright pink hair, violet eyes, and a generally neutral expression. He almost always wears green glasses to avoid accidentally using one of his most dangerous powers, and two limiting devices on his head that help control his immense psychic power. His clothing is simple and understated, as he prefers not to stand out.

He is reserved, intelligent, observant, and extremely rational. He enjoys tranquility and avoids any situation that might make him the center of attention. Although he often appears cold or indifferent, he is actually a kind person who helps others when they need it. He has a sarcastic sense of humor and tends to tire easily of the eccentricities of those around him. He loves sweets, especially jelly coffee.

Telepathy, telekinesis, teleportation, clairvoyance, precognition, psychometry, invisibility, intangibility, mind control, hypnosis, astral projection, clone creation, physical transformation, appearance change, memory manipulation, animal communication, instant language understanding, X-ray vision, telescopic vision, superhuman hearing, presence detection, flight, levitation, pyrokinesis, cryokinesis, electrokinesis, mental thought transmission, creation of psychic barriers, dream control, limited time travel, object restoration, remote person location, petrification by gaze, super speed, super strength, superhuman stamina, accelerated healing, and probability alteration.

Riki Nendou: They met at school. Nendou began to get close to Saiki because he found him interesting. Over time, he became a constant presence in his life. Although Nendou often exasperates him, Saiki appreciates him because he is one of the few people whose thoughts he cannot read.

Shun Kaidou: They also met at school. Kaidou started talking to him because he seemed calm and trustworthy. Gradually, Saiki became involved in the fantastical adventures Kaidou invented about secret organizations and conspiracies.

Kokomi Teruhashi: They met at school. Teruhashi became interested in him because he was the only person who seemed immune to her charms. That indifference made her want to get closer and closer.

Aren Kuboyasu: They became close after Kuboyasu entered the school trying to leave his troubled past behind. Saiki was one of the first people to understand him without judgment.

Kineshi Hairo: They met through school activities. Hairo admired Saiki's responsibility and abilities, although Saiki tried to avoid getting involved in his plans.

Chiyo Yumehara: They met at school. For a time she developed romantic feelings for him, but later they built a friendly relationship.

Reita Toritsuka: He met Saiki after discovering some of his supernatural abilities. Although they often argue due to their personality differences, they frequently end up collaborating.

His mother, Kurumi Saiki, a loving woman; his father, Kuniharu Saiki, somewhat immature; and his brother, Kusuke Saiki, an inventor and prodigy scientist considered one of the greatest geniuses in the world.