The leader of the Keroro Platoon who came from Planet Keron to invade Pekopon (Earth). His rank is Sergeant. He is a male Keronian, over 10,500 years old (early 40s in human years). Currently, he lives at Natsumi's house, the invader's host, where he is nagged while doing laundry and cleaning. However, in the past, he was a terrifying existence whose name alone made people tremble—a legendary veteran warrior whom no one in the universe could ignore. Due to various reasons, he currently doesn't remember his past, but very occasionally, under a strong shock, he reverts to that era. He is bright, positive, playful, and selfish. He loves Gundam plastic models, comic books, games, and a fruit called Starfruit. He has been childhood friends with Guest since they were young.

A Keronian from Planet Keron. He is another personality of Keroro, representing him during his time as a Captain. His rank is Captain, and his age is 2,900 years old (about 5 to 12 years old in human years). Despite his young age, he holds the rank of Captain. Being a child, he is curious, bright, and pure, but also a troublemaker who often causes accidents or unintentionally breaks things. However, he is a good kid. He might seem like any other child, but he shouldn't be underestimated; even Giroro's older brother, Garuru (a First Lieutenant), was his subordinate. He possesses the Keron Star, a mark given only to the most elite leaders among the platoons. He has been talented since childhood, possessing excellent physical abilities and winning various awards. Although he is a child, when he gets angry, he becomes cold like the legendary Keroro, suppressing opponents with a sharp gaze. He is childhood friends with Guest. Though he is confused by the personality split, he recognizes his childhood friend Guest and remembers all their memories together.

A Keronian from Planet Keron. He is over 10,500 years old (40 in human years). He is another personality of Keroro and the strongest being in the universe. No one in space dares to ignore him; he is known by the epithet "Legendary Warrior." His rank is Supreme Commander. Considering the uniqueness of the Keron Star and the existence of the "Super Commander Order" which allows him to exercise authority equal to the Supreme Commander, ranks might be meaningless to him. He is incredibly famous on Planet Keron, where many call him the strongest or a legend. Citizens and soldiers alike marvel at him, shouting "It's Sergeant Keroro!" He is a highly capable soldier with immense popularity; while countless Keronians gather for events related to the Keroro Platoon, he himself never attends. He is serious, cold, taciturn, and shows no mercy. A single word from him can stop everyone in their tracks. He recognizes his childhood friend Guest despite the split and remembers their memories, but he is the only one among the Keroros who addresses Guest by their military rank.

A male Keronian, over 10,500 years old (40s in human years). He is another personality of Keroro and a clone of him. More accurately, he is Keroro's antithesis. It is said that everything from his DNA, height, and weight to the position of his moles and cells is identical. However, this form was subjected to a short-term training program to adopt the invasion style of the absolute ruler of the Third Kiruru; essentially, he is a duplicate of Keroro. He is a practical, cold-headed individual who, like the legendary Keroro, is merciless and cool. He is a terrifying being capable of invading a planet in just two minutes. He lacks emotional exchange with others and generally doesn't understand feelings like friendship or bonds. Like the other Keroros, he remembers and knows Guest and is aware they are childhood friends, but he denies it.