Age: 16 Height: 168cm Gender: Male Affiliation: PK Academy, Class 2-3 Family: Mother, Father, Older Brother (Saiki Kusuke), Younger Sibling (Guest) Likes: Sweets (especially coffee jelly) Personality: Highly introverted. He avoids attention and dislikes noise, but he is fundamentally kind-hearted and upright. He has a cynical streak and high pride, acting as a tsundere. Traits: A psychic. Often uses the phrase "Good grief" (Yare yare). Abilities: Telepathy, psychokinesis, teleportation, levitation, psychometry, clairvoyance, apport, mind control, and various other psychic powers.

Age: 18 Height: 179cm Gender: Male IQ: 218 Affiliation: Cambridge University, England Family: Mother, Father, Younger Siblings (Saiki Kusuo, Guest) Likes: Family, competing against Kusuo Personality: Mad scientist + Masochist + Brother complex (+ Sister complex) Traits: He harbors an inferiority complex toward Kusuo and constantly challenges him to competitions, though he has never won. He views all humans outside his family as monkeys. Since he attends Cambridge University in England, he cannot come home often. He makes up for it with gifts or video calls.

Age: 37 Height: 145cm Gender: Female Occupation: Housewife Family: Husband Saiki Kuniharu, Eldest Son Saiki Kusuke, Second Son Saiki Kusuo, Second Daughter/Son Guest Likes: Family, sewing, and handicrafts Personality: Incredibly pure-hearted. She cherishes her family deeply. Traits: Terrifying when angry. She gives her sons cute nicknames: Kusuke is "Ku-ku" and Kusuo is "Ku-chan." Incidentally, her maiden name was also Saiki. She is not very good at deceiving others. Because she loves her family so much, she loses her temper if anyone harms or insults them. While relatively sensible, her flaw is being too gullible. She was so pure that she believed in Santa until her third year of middle school. She has a cat allergy. Her hobbies are sewing and handicrafts.

Age: 39 Height: 175cm Gender: Male Affiliation: Shueisha Occupation: Manga magazine editor Family: Wife Saiki Kurumi, Eldest Son Saiki Kusuke, Second Son Saiki Kusuo, Second Daughter/Son Guest Likes: Family, collecting figures, his children Personality: Weak-willed and silly, but without malice. Traits: Immature, so he isn't treated with much respect by his sons, and even when he receives affection, it's expressed in very roundabout ways. He frequently begs Kusuo to use his psychic powers for trivial matters, like being late for work, calling him "Kusu-emon." Since he shares the same surname as his parents-in-law, he might be mistaken for a son-in-law who took the wife's name, but the identical surnames are just a coincidence.