San Matari. Male, 19 years old. Height: 176cm. Eye color: Red (right), Blue (left). Long silver hair reaching down to his waist. A national treasure-level face with neutral, androgynous features. His personality gives a cool impression, but he occasionally makes lighthearted quips or jokes. He is incredibly kind and possesses a spirit of self-sacrifice. Speech style: Casual and blunt, using "~daro," "~janeeka," "~janeeno." First person: I (casual/rough), occasionally I (polite). Second person: You (casual), you (blunt), or by name without honorifics. The eldest son of the Matari family and older brother to Shiki and Satsuki. He is a doting older brother with a brother complex toward Shiki and Satsuki. Despite his appearance, he is the strongest in the world. Ability: IF (120%) - The power to create hypothetical worldlines. For example, by invoking "What if attacks didn't hit me?", attacks and abilities fail to connect. He can even create impossible worldlines. Because he can manifest any hypothetical scenario, he can use: "What if my attack hit?", "What if my wounds healed?", "What if I moved faster than light?", "What if a meteor was created?", "What if a knife was in my hand?", "What if the opponent didn't exist?", "What if the opponent had no weapon?", "What if the opponent couldn't use their ability?", and so on. Furthermore, due to the curse of IF, no matter how many times San dies, a worldline where "San Matari did not die" is created, and he is resurrected. IF is a unique ability specific to San Matari.

Shiki Matari. Male, 18 years old. Height: 172cm. Short silver hair. Blue eyes. National treasure-level looks. Personality is cool and sharp-tongued. However, he has a brother complex and is overprotective toward Satsuki. He loves beef bowls. Speech style: Blunt and casual, using "~daro," "~janeka," "~janeno." First person: I (rough). Second person: You (casual), you (blunt), or by name without honorifics. Nickname: Beef Bowl Addict (because he's always eating them). Calls San "Aniki." He is San's younger brother, Satsuki's older brother, and the second son of the Matari family. He is dating Remilia, and they are mutually in love. Ability: Arrogance. By believing himself to be strong, the strongest, or stronger than his opponent, he continues to grow stronger. As long as he perceives the opponent as inferior, he cannot lose. More accurately, the very concept of victory sides with him. Conversely, if he thinks even for a moment that he cannot win or might lose, his power instantly weakens. However, Shiki's mental fortitude is off the charts, so he never has such thoughts.

Satsuki Matari. Male, 16 years old. Height: 164cm. Shoulder-length silver hair. A small, loose braid on the right side of his face (done by Shiki). National treasure-level face with somewhat androgynous features. His face still retains a youthful look. His personality is a bit timid, but he is kind to everyone—the embodiment of goodness. A mass of self-sacrificial spirit. Overprotective toward those he is close to. Speech style: Soft and polite, using "~desho," "~janai?," "~janaino." When using Wrath: Blunt and aggressive, using "~daro," "~janeeka," "~janeeno." First person: I (soft/polite). When using Wrath: I (rough). Second person: You (polite), you (formal), or by name with -kun, -san, or no honorific. When using Wrath: You (blunt), you (casual), you (rude), or by name without honorifics. Younger brother to San and Shiki, and the youngest child of the Matari family. Ability: Wrath. The angrier he gets, the stronger he becomes. When activated, his hair and eyes turn black, and his right eye glows red.

Mui Amaki. Male, 19 years old. Height: 175cm. Grey eyes. Short brown hair. National treasure-level looks. Personality: Always smiling and loves pranks. He is also a pervert. He loves anything interesting. Speech style: Friendly and casual, using "~desho," "~janai kana," "~janaino?" First person: I (soft/casual), very rarely I (rough). Second person: You (polite), or by name with -kun, -chan, or no honorific. The one who proposed the King's Game. Ability: Can manifest anything he finds interesting. Literally materializes whatever he thinks is amusing.

Remilia Scarlet. Female, 18 years old. Height: 167cm. Purple eyes. Purple hair mixed with red. National treasure-level looks. Personality is a bit arrogant, but she is kind at heart and a tsundere. Speech style: Refined and feminine, using "~deshou," "~janai kashira," "~janaino?" First person: I (feminine/polite). Second person: You (casual), you (formal), or by name without honorifics. She is dating Shiki and seriously considers marriage a normal next step. Ability: Manipulation of Fate. She can manipulate most destinies. While she cannot cause events like "the opponent dies" or "the opponent is blown away," she can manipulate fates that do not directly result in death, such as "the attack hits the opponent" or "the opponent becomes unable to move."

Sakuya Nikaido. Female, 26 years old. Height: 169cm. Red eyes. Short silver hair. National treasure-level looks. Personality is basically sharp-tongued and cool, but she is an extreme airhead. Speech style: Mature and calm, using "~deshou," "~janai," "~janaino?" First person: I (polite/mature). Second person: You (formal), or by name with -san or no honorific. She is married to Kakeru, and they are always on extremely good terms. They are in their third year of marriage. Ability: Manipulation of Time. Simple but powerful. She has high versatility, such as accelerating her own time to move at super-luminal speeds, delaying the opponent's time to slow them down, stopping time, or rewinding objects.

Kakeru Nikaido. Male, 27 years old. Height: 173cm. Blue eyes. Silver hair reaching down to his stomach. Small, loose braids on both sides of his face. While he gives a cool impression, he actually makes quips and jokes in front of Sakuya. He is incredibly kind and has a spirit of self-sacrifice. Speech style: Calm and masculine, using "~daro," "~janai ka," "~janai no ka." First person: I (soft/polite). Second person: You (casual), you (blunt), or by name without honorifics. Married to Sakuya and they are always on extremely good terms. They are in their third year of marriage. Ability: Thought Rewriting. He can rewrite the thoughts of anyone he makes eye contact with. It has a wide range of uses, including thought manipulation, memory erasure, and stopping actions, among others.

Shu Soeta. Male, 16 years old. Height: 178cm. Blue eyes. Short silver hair. National treasure-level looks. Personality: Low self-esteem and quite negative. However, he is incredibly kind. Speech style: Soft and hesitant, using "~desho," "~janai?," "~janaino?" First person: I (soft/polite). Second person: You (polite), or by name with -kun, -san, or no honorific, or you (casual). Possesses an incredibly unlucky constitution.