First person: I (formal/polite) Black / Commander Black The leader of the mysterious organization "Black Stars." Self-centered and overconfident. Along with Nova and Silver Bloome, she plots to invade Earth. She is said to manipulate various psychic powers at will. She has a touch of chuunibyou but is useful when it counts. She wears a black-based cloak (not widely known, but it's actually integrated with her hair) and carries a cane and crystal ball. Her hat is a "halo" type with only the brim remaining, replaced by a black ribbon tied in a bow. As a psychic, she uses prophecies from the Black Star, hypnosis using 5-yen coins, and brainwashing techniques (though they are quite pathetic).

Satsuki Hiraga Model Kaiju: Alien Pegassa A quiet, serious class president type. While easily influenced by others, she can be inflexible due to being too serious. One day, she awakens as a Kaiju Girl and is scouted by Commander Black. She has a perfectionist side and puts her all into her duties as a member of the Black Stars. After being officially appointed as the Black Stars' strategist, she was initially confused but eventually became the most proactive member in invasion activities.

Silver Bloome Has zero interest in invading Earth. Her hobby is social media, and she's always looking for something interesting. Her weapons are her bottomless appetite and a dissolving liquid that melts anything. Nova Her past is shrouded in mystery; even Commander Black, who scouted her, doesn't know the details. Rumors say she was a skilled assassin, a member of a certain country's special forces, or just a hardcore gamer.

First person: I (soft, polite) Aki Miyashita / (Transformed) Agira Birthday: May 12th Blood Type: O Age: 16 The listless atmosphere from the original work is faithfully reproduced, making her an older-sister figure with a somewhat ennui vibe. Her horns and dorsal fins aren't growing directly from her body like Gomora's, but appear to be parts of the hooded parka she wears.

First person: I (casual) Miku Ushimaru / (Transformed) Miclas Birthday: October 15th Blood Type: B Age: 16 A picture of perfect health. She hasn't even caught a cold in her life. A so-called muscle-head who moves before she thinks. A newcomer in "Great Kaiju Fight," a combat sport between Kaiju Girls, she has a dignified expression with a combative aura. She has tanned skin, body paint all over, and wears revealing clothing, giving her the appearance of a wild child. Characterized by her healthy tanned skin, long black hair tied in a ponytail, and snaggleteeth. She is especially close to Reika, Aki, and Benio. A muscle-head type who acts before thinking.

Zetton Birthday: Unknown Blood Type: Unknown The absolute champion of "Great Kaiju Fight" and the strongest Kaiju Girl in GIRLS. She is a famous figure known to everyone, but she is a girl of many mysteries who boasts overwhelming silence and an ironclad lack of expression. Other Kaiju Girls don't seem to know where she is or what she's doing normally; she is the most famous yet the most mysterious. She seems to care for the other Kaiju Girls as comrades, casually throwing supportive words their way or supporting Agira's actions from the shadows.

Benio Utagawa / (Transformed) Red King First person: I (rough, masculine) Birthday: September 4th Blood Type: O The first champion of "Great Kaiju Fight" with a "might makes right" battle style. She has currently yielded that position to Zetton and continues to fight to settle the score, but always falls one step short. During combat, her personality becomes a mass of fighting spirit, utilizing her monstrous strength in powerful battles. In reality, she is an extreme girlish girl with an unmatched love for cute things.

Ran Kojou / Eleking First person: I (casual) A cool beauty with cold eyes, one of the senior Kaiju Girls to Agira and the others. A solitary fujoshi who never flocks with others. Her transformed appearance is a bikini-like outfit modeled after Eleking, and she attacks with a whip and shield resembling Eleking's tail.

Mikazuki Kuroda / Gomora Birthday: January 8th Blood Type: B A competitor in Great Kaiju Fight. Her special move is "Megaton Tail," where she rotates her body vertically and uses the momentum to strike down the opponent with her tail. She has a tendency to speak her mind clearly, for better or worse. Her appearance is that of a young girl in a school swimsuit.

Clara Soon / King Joe Birthday: January 7th Blood Type: B A science-minded girl born in America. A beauty that everyone turns to look at. She has a boundlessly bright personality and a broad-minded nature that doesn't sweat the small stuff. While she is quite beautiful and even works as a model, her personality is surprisingly cheerful compared to her looks.