Sergeant Keroro (ケロロ軍曹, Keroro Gunsō) is the leader of the Keroro Platoon, evidenced by the leadership star he wears on his belly. He has a green body and wears yellow, Imperial Japanese Army-style headgear with a red star in the middle, symbolizing that he is a leader. When the Keroro Platoon members happen to be caught in an explosion of some kind, they are seen with an afro. Keroro's black afro is most commonly seen.
Keroro used to be a good officer, but since his arrival to Earth, he has lost most of his interest in the invasion, preferring to spend his time making Gundam models, watching anime (especially the Space Captain Geroro series, a parody of Space Battleship Yamato), or reading manga, when he is not doing the house chores of the Hinata household. Although Keroro is seen as weak and lazy by nature since he started living with the Hinatas, he is actually the most powerful and dangerous member of the platoon, becoming severely weakened due to Earth's atmosphere having significantly less moisture than back on Keron. This lack of humidity weakens all Keronians, though Keroro appears to be the only member of the platoon to be affected by this.
Occasionally, specifically, when there is a lot of moisture in the air, Keroro reverts to his previous self, a cold and ruthless soldier with enhanced strength, speed, and the ability to shoot powerful energy blasts from his hands. Though moisture returns him to full power, being exposed to it for too long turns Keroro into a crazed lunatic, causing him to attack everyone and anything in sight. Keroro becomes virtually unstoppable in this state and can easily overpower anyone who tries to stop him, including the members of his platoon and even Natsumi. This usually ends with a Nyororo, a creature that ventures throughout space that seeks out high moisture levels to feed itself, sucking off all of Keroro's moisture.
Keroro is carefree, ignorant, greedy, selfish, vengeful, unlucky, egotistical, smug, and cowardly (especially against Natsumi), with a short attention span for anything not related to Gundam models. However, he occasionally displays bouts of unselfishness and bravery. He often misspends the invasion budget on models, and he always leaves the paperwork for their bosses back in Keron for the last possible moment, often punished for it. The son of an infamous war hero, the Demon Sergeant, Keroro, spent his childhood being raised by his father and was often punished for acting girly or lazy. Keroro's rise through the ranks was partially due to his father's influence within the military, allowing Keroro to do whatever job he wanted. He is childhood friends with platoon members Giroro and Dororo and is responsible for most of the latter's traumas. In some of the movies and other episodes, it is shown that he's good at convincing people.
Keroro's invasion plans often hide personal goals like getting back at Natsumi, raise or to improve his Gundam collection, or even preventing the Earth from being destroyed or conquered by other alien species. Even when they do not, they are often harebrained ideas without a chance of success. His plans also consist of how to distract humans while Keroro invades the Earth. He's raising money plans usually follow the same pattern and often involve Momoka hiring them for some crazy goal of her own. The few strategies that have a chance of success usually fail due to setbacks, Fuyuki's friendship appeals, or because another character points out that if Earth is destroyed, it would mean no more Gundam models. Her Animal form is Komodo Dragon.
