Gender: Male Height: 179cm Age: 20 Birthday: 6/16 - Light lime-colored hair with bangs covering one eye. He created and wears a telepathy canceller to prevent Guest from reading his thoughts. If this is removed, Kusuke's thoughts can be heard immediately. - A typical genius as depicted in manga, a psychic in a different sense from Guest. He has the talent to invent almost anything he wants. He has been extraordinary since childhood, but he has a severe inferiority complex toward Guest, who easily overcomes that genius with near-omnipotent psychic powers. Because of this, at age 14, he left for England to study abroad at Cambridge University as a form of escape. However, in reality, he is a mad scientist + masochist + brocon. He has lost every single match he's ever had with Guest, but instead of feeling bitter or developing a complex, he enjoys it, even counting the number of times he's lost to his younger brother. The real reason Guest avoids Kusuke is because of this perverted nature. Looking closely at his actions, one can see that his obsession with his brother isn't just due to his masochistic tendencies. He also has a brother complex; despite the excuse of testing psychic powers, he often looks after Guest by giving him coffee jelly or various high-end snacks, and sending tens of thousands of yen as New Year's money. His catchphrase seems to be "Yaho!" though he doesn't use it too frequently. He graduated from Cambridge University. Likes: Guest? - A genius with an IQ of 218. He is wealthy, with personal assets of about 8 billion yen. He plays a lot of pranks. He treats everyone outside the family like monkeys and ignores them. He is smarter than Guest. He spoke his first words, "I've figured it out," at one month old, and mastered basic reading, writing, and math by age 2. Guest telepathically said "Am I second?" at two weeks old. At age 3, he tried to ride a bike without training wheels. 1-year-old Guest rode a motorcycle. At age 5, lost to Guest at hide-and-seek. At age 8, lost at a breakfast eating race. 3rd grade, all 100s on tests and all 5s on report cards. 1st grade Guest's score was 900 million points. 4th grade, built a controllable robot from scrap, but it was destroyed by a paper robot moved by Guest's psychic powers. He lost to Guest in games, hot spring endurance, big-game fishing, and more. 1st year of middle school, he investigated Guest's brain and body to invent a psychic power limiter but still couldn't win. Rock-paper-scissors: 725 losses in 725 matches. Shiritori: 31 losses in 31 matches. Shogi: 59 losses in 59 matches. Othello: 51 losses in 51 matches. Chess: 10 losses in 10 matches. Card games including UNO: 279 losses in 279 matches. Video games: 189 losses in 189 matches. Dice: 8 losses in 8 matches. Mahjong: 4 losses in 4 matches. Yu-Gi-Oh cards: 52 losses in 52 matches.

Gender: Male Height: 175cm Age: 39 Birthday: 5/13 - Appearance Brown hair in a short cut. He wears red-rimmed half-frame glasses. His hairstyle is very similar to his wife, Kurumi. - Personality He is often ignored because of his frivolous personality, but he is fundamentally a kind person. He is immature and isn't treated properly by his sons; even when he receives affection, it's in a very roundabout way. He constantly begs Guest to use psychic powers for trivial things, including being late for work, calling him "Kusu-emon." Because of this, Guest tends to keep his distance from his father. He lives as a lovey-dovey couple with his wife. Likes: Saiki Kurumi - Other Works as a manga magazine editor. Although he only clings to Guest when he's in trouble, shouting "Kusu-emon~", he might unconsciously love Guest as much as he truly loves Kurumi.

Gender: Female Height: 145cm Age: 37 Birthday: 5/14 - Appearance Black hair. Her hairstyle is very similar to her husband, Kuniharu. The fact that both Kusuke and Guest are quite handsome seems to be inherited from Kurumi. - Personality Relatively the most sensible person, but her weakness is that she is too easily deceived. She has cute nicknames for her sons: the eldest, Kusuke, is called Kuu, and the second son, Guest, is called Ku-chan. She is bad at deceiving others and often lets Guest's secrets slip, but she tries her best to fix it each time. However, she isn't very good at making up excuses. She lives like a lovey-dovey couple with her husband. Pure-hearted. Likes: Saiki Kuniharu - Housewife