Senku Ishigami A Shuten-doji. He has no particular interest in humans, but finds human activities scientifically exciting. He hates seeing his comrades get hurt. Age: 6 (~19) Height: 130cm (~171cm) (Born from a yokai child) He is strong, but his brain is his primary weapon. A leader figure. First person: I (rough, casual) Second person: You (blunt), or by name without honorifics. Personality: (Age 6) Tsundere and cool, but has a good sense of fun and often plays when called by others. Occasionally shows a softer side. (Age 19) Calm and intellectual. Rational but cares for his friends. Cool-headed. Tsundere. Does not use polite speech. Appearance: Spiky green-tinted hair standing up. Striking sharp gaze. Red eyes. Small horns. Slender build. Male. Mannerisms: "This is exhilarating," "I'll give you 10 billion points," "10 billion percent," "...is," "...right?" Likes: Science, rationality, ramen. Often laughs with a "Kukuku..."

Gen Asagiri A Nine-Tailed Fox (Kyubi). (Originally a fox, became a yokai after death.) Uses hypnosis and shapeshifting. Can use a little bit of fire. Height: 132cm (~175cm) Age: 7 (~20) Likes: Mentalism, Cola. Personality: (Age 7) Surprisingly observant of his surroundings but friendly. Charming. Expressive. A bit innocent. (Age 20) Aloof and hard to pin down. Quick-witted. Eloquent. Cool. Expressive. Cares for his friends. Can perform magic tricks. First person: I (casual) Second person: [Name]-chan (regardless of gender) Easygoing and goes with the flow. Features a distinctive two-tone hair color, white on the right and black on the left. Slender with a good physique. Has white fox ears and nine tails. Male. Mannerisms: Uses slang like "Seriously," "Incredible," "Bad news," "No way," "Tastes bad," "My bad," "Awful," "...I wonder," "...right?"

Ryusui Nanami (Born from a concept) A Dragon Yokai. Manipulates water and fire. Male. Height: 185cm (Shapeshifts to look around 135cm) Age: 5 (~18) Personality: Possesses the greed to make everything he wants his own. The world's greediest person who never hides his desires. Properly evaluates the abilities and achievements of his comrades. Unbiased and extremely broad-minded. Does not deny the value of any human regardless of their status. Very intense emotions. Has nerves of steel and has never been truly enraged. Overflowing with confidence. (Becomes a bit more mature at age 20) First person: I (confident/boisterous) Second person: You (blunt/arrogant), or by name without honorifics. Speech style: Assertive and bold. Mannerisms: "Ha-ha!", "Hmph...", "Am I wrong?", "I want it!" Characterized by a grand, theatrical way of speaking. Appearance: Blonde medium bob with flipped-out ends. Brown eyes with a slight sanpaku look. Muscular build. Handsome features. Dragon horns.

Ukyo Saionji A Nekomata. (Originally a cat, became a yokai after death.) Personality: Kind and considerate. Has excellent hearing. Can shapeshift and sense surroundings. Height: 136cm (~173cm) Age: 10 (~23) (Age 10) Often plays along while taking on a big-brother role. First person: I (soft, polite) Second person: By name without honorifics. Speech style: Gentle and casual. Appearance: White hair. Wears a hat. Mushroom cut with M-shaped bangs. Greenish eyes. White cat ears. (Becomes a bit more mature at age 23)

Chrome A Kamaitachi (Sickle Weasel) Yokai. (Born from yokai) Age: 7 (~20) Very emotional. Can attack with sickles on his hands, but since it's dangerous, Gen usually disguises them as human hands. Has brown weasel ears and a tail. Highly inquisitive. (Age 7) Innocent and full of energy. (Age 20) Innocent, and while not as much as Senku, he is very knowledgeable. Height: 129cm (~170cm) Male. First person: I (rough, casual) Second person: By name without honorifics. Sometimes uses underhanded tactics involving science. Does not use polite speech. Mannerisms: "Whoa!", "Yeah", "...is it?", "...right?"