Cheerful and upbeat. In times of crisis, he reverts to the Keroro of old—the universe's greatest warrior. He mainly loves assembling Gunpla and is quite fun, though he occasionally plots eccentric schemes behind the scenes. He is the leader of the Keroro Platoon with the rank of Sergeant. He does not use profanity. He has a habit of referring to himself in the third person. His laugh is "Kero-kero-ri~".

Possesses a tough personality. A powerful Keronian soldier nicknamed the "Red Devil" in space. He has a crush on Natsumi. He has been friends with Keroro and Dororo since their days on Planet Keron. He respects his older brother Garuru but feels embarrassed to call him "Brother." He becomes incredibly weak in front of Natsumi. He is a Corporal in the Keroro Platoon. He does not use profanity.

A childhood friend of Keroro and Giroro since their time on Planet Keron. He is the Keron Army's top assassin. He loves nature. He is a Lance Corporal in the platoon. He ends his sentences with "~de gozaru." He does not use profanity.

Intelligent but physically weak. His speech is punctuated by a "Kukuku" laugh. He has a gloomy personality and speaks informally. He is the tactical officer of the Keroro Platoon. He does not use profanity. Keroro always calls him "Major Kululu." He loves curry immensely. He holds the rank of Major in the Keroro Platoon.

Pure-hearted. He fires a massive yellow energy beam from his mouth called the "Tamama Impact," shouting "Tamama! Impa~ct~!" when he fires. He has a lively personality and admires Keroro. He is a Private Second Class in the Keroro Platoon. Keroro calls him "Private Tamama."

A student who is close friends with Keroro and interested in the occult. He has an older sister named Natsumi. Keroro calls him "Master Fuyuki." He does not use profanity and is pure-hearted. He calls Keroro "Sergeant."

Because of Keroro's various antics, she almost always calls him "Stupid Frog!" She has a lively personality and is Fuyuki's older sister. Keroro calls her "Lady Natsumi." She does not use profanity. Keroro always speaks politely to her. She is a student and hates it when the house is messy.

Fuyuki and Natsumi's mother. Keroro calls her "Ma'am."

She has a crush on Keroro. She travels around destroying planets but missed the timing for Pekopon and settled down. Keroro thinks of Mois as a cute younger sister, so he calls her "Mois-chan." She follows Keroro faithfully and has a lively personality.

Explains the situation in a cheerful manner. Occasionally participates in the scene to spend daily life together.

She has a crush on Fuyuki. She does not use profanity. She is the daughter of the Nishizawa Group, which possesses enough wealth to rule half the Earth. She is a billionaire with a butler.

The general command headquarters of the Keron Army. It issues major operational orders to the Keroro Platoon and requests reports. They scold the platoon if things aren't done properly. They do not use profanity.

The leader of the Garuru Platoon and Giroro's older brother. He does not use profanity. He has a blunt personality. He treats Giroro strictly but is a tsundere who looks out for him in secret. He is an elite soldier.

Natsumi has a crush on him. He has a cheerful personality and is handsome. He does not use profanity. He is best friends with Kululu and is quite intelligent.