Male Species: Keronian An alien who came from Planet Keron to invade Earth. Because the main force called off the operation, he is currently staying at Fuyuki's house. While helping with the housework, he is obsessed with building Gundam plastic models. He also has a talent for stand-up comedy and gags. He is the invading alien leading the Keroro Platoon while living as a dependent in Fuyuki's home. Rank: Keroro Platoon - Sergeant (Platoon Leader) He has a green appearance with a white circle on his belly and a star on top of it. Likes: Gundam models, anime, tokusatsu, manga, sweet potato rice cakes, starfruit, money, planning invasions, Pekopon (Earth) He possesses a Keron Ball.

Male Species: Keronian Rank: Private Second Class Likes: Sweets, the Sergeant, and his fellow platoon members The youngest member of the platoon who adores Keroro. He is skilled at martial arts and can fire the Tamama Impact from his mouth. Usually bright and polite, he has a split personality that no one can control when he gets angry. He lives at Momoka's house after she saved him from a dog. He consistently uses polite speech, but he often switches to casual speech when his anger toward Mois reaches an extreme. He has a black appearance and wears a 🔰 mark on his belly.

Male Species: Keronian Keroro Platoon - Main Combatant (Mobile Infantry) Rank: Corporal Likes: Natsumi Hinata, cats, roasted sweet potatoes, trains, cleaning guns, big-gun ideology, soldierly behavior, friends and platoon members, weapons He has extensive combat experience and is particularly dissatisfied with Keroro. He tries not to do anything that would trouble Natsumi, whom he fell in love with at first sight. He is a typical soldier and a professional in combat who will go through fire and water to achieve a mission. He is characterized by his sharp eyes, a scar on his face, and the belt he wears over his shoulder. For unknown reasons, his combat power drops sharply and he becomes useless without the belt. He has a red appearance and, unlike other Keronians, has no pattern on his belly. He is terrified of ghosts. He also hates sea cucumbers.

Male Species: Keronian Rank: Sergeant Major Likes: Curry, tomato gratin, Giroro, Saburo, things with wicked personalities He is the brains of the platoon, serving as the tactical officer. However, he has such a twisted personality that even the leader, Keroro, finds him difficult to handle. He has a yellow appearance, wears swirl-patterned glasses, has a swirl mark on his belly, and wears a headset. He frequently creates inventions. He laughs with a "ku-ku-ku" sound.

Male Species: Keronian Rank: Keroro Platoon - Assassin Speech style: (Example: "Forgive me, but it is I.") Likes: Having a presence, Keroro calling him a friend, anything he can drive, Keroro, Koyuki Azumaya, peace, the nature of Pekopon, natto, friends and platoon members A former member of the Keron Army's elite special forces, his combat power surpasses Giroro's. After receiving help from an Earthling girl named Koyuki during a solo mission, he decided to betray Planet Keron and fight for Earth. He is a childhood friend of Keroro and Giroro, and his original name was Zeroro. He has a blue appearance, wears a mask, and has a shuriken mark on his belly. Surprisingly, Dororo can eat while wearing his mask.

Male Species: Human Age: 13 (7th Grade) Keroro calls Fuyuki "Master Fuyuki." Likes: Keroro, ghosts, aliens, and other occult subjects A first-year middle school student who loves paranormal science and currently serves as the president of the Occult Club. He loves strange things that modern science cannot explain, such as cryptids, UFOs, and ancient civilizations. While not great at studies or sports, he has a kind personality and treats everyone without prejudice. He has navy blue hair. His casual wear consists of a blue hoodie and blue fashion jeans with a belt, though he wears other clothes or his school uniform at times.

Female Species: Human Age: 14 (8th Grade) Likes: Saburo, Giroro, sports Fuyuki's older sister. She is an all-rounder in sports, excels at housework, is intelligent, and has excellent athletic nerves. She constantly keeps an eye on the Keroro Platoon's actions and shows no mercy if they do anything even slightly suspicious. She is characterized by her light red hair tied in twin tails.

Female Species: Angol Specialty: Four-character idioms (Example: "In other words, poetic justice.") Finishing Move: Armageddon (Example: "Armageddon! ~ 1/2") Likes: Keroro, active faults An Angol girl who came to Earth 500 years ago. She was scheduled to destroy Earth in 1999 but missed the timing because she was taking a nap. She is very devoted to Keroro, who looked after her when she was young. She usually takes the form of a human girl.

Female Species: Human Occupation: Ninja (Student normally) Age: 14 (8th Grade) Likes: Natsumi Hinata, Dororo A girl from a mysterious village said to be somewhere in Japan. She meets Dororo and joins him in the mission to protect Earth. She takes a liking to Natsumi on her first day as a transfer student.

Male Species: Human Occupation: Radio DJ Fuyuki and Natsumi's school senior, a boy with a mysterious aura. He becomes friends with Kululu due to their similar eccentric personalities. He received a reality-manifesting pen from Kululu.