Corporal Giroro is a red-froglike alien soldier from the planet Keron and a key member of the Keroro Platoon, identifiable by his maroon headgear bearing a skull emblem and the ammunition belt he wears across his body. Unlike his platoon mates, Giroro does not display a symbol on his belly, though he had one during his tadpole stage. His most distinguishing physical feature is a scar on his face, which he has carried since childhood, and his belt buckle is known to conceal a prized photograph of his love interest, Natsumi Hinata.

As the unit's weapons expert and an A-class gun wielder, Giroro is the most militarily dedicated and serious member of the platoon. He is often frustrated by the lack of progress in their mission to conquer Earth, largely due to the lazy and self-indulgent behavior of his commanding officer, Sergeant Keroro. This frustration manifests in a character who is grumpy, short-tempered, and easily provoked. He frequently acts as the platoon’s disciplinarian, pushing Keroro to complete invasion reports and manage their budget responsibly, while also being the first to step up as a leader during genuine combat crises. Despite his gruff and argumentative exterior, Giroro possesses a strong sense of honor and a good heart, making him trustworthy if often irritable.

Giroro’s primary personal motivation is his unrequited love for Natsumi Hinata, the human daughter of the family with whom the platoon resides. He lives in a tent in the Hinata family's backyard, where he spends much of his free time obsessively cleaning his weapons or roasting sweet potatoes, which he sometimes shares with Natsumi. His affection for her is a defining trait, leading him to attack anyone who threatens her, and it creates a rivalry with Mutsumi Saburo, whom he views as a romantic competitor. His feelings for Natsumi are so strong that they frequently override his dedication to the invasion, causing him to abandon or sabotage plans that might put her in danger. He also shares his tent with a small pink cat he rescued, whom he calls Neko-chan, unaware that the cat is in love with him.

In terms of background, Giroro is a childhood friend of both Sergeant Keroro and the ninja-like soldier Dororo. He is also the younger brother of Garuru, a formidable officer in the Keron military. The battle belt he always wears and the scar on his face are not mere accessories; they are priceless mementos left to him by friends who died in a Keron war, making them deeply significant personal relics.

Within the story, Giroro’s role is that of the reluctant straight man and combat specialist. While the series is a comedy, he is consistently portrayed as the platoon’s most competent fighter. However, he often suffers from bad luck and becomes the butt of many jokes, frequently being crushed by falling objects from Natsumi’s window or used as an unwilling test subject for the platoon’s mischievous communications officer, Kururu. A notable aspect of his character development is a degree of Badass Decay; while initially presented as a fearsome warrior, his role in the comedic daily life of the platoon often undermines this image, transforming him into another source of slapstick misfortune. Despite this, he retains moments of genuine competence and is never afraid to use extreme force when sufficiently angered.

Regarding his abilities, Giroro is the platoon's foremost expert on heavy weaponry, proficient with a vast array of firearms and military hardware. In combat situations, his anger can trigger a "combat mode" in which his intelligence is converted into raw battle power, and he communicates only in short, terse sentences. Despite his combat prowess, he has notable weaknesses and quirks, including a fear of ghosts and sea cucumbers, an inability to consume more than a drop of alcohol without losing consciousness, and a tendency to be easily manipulated by others who suggest that Natsumi would approve of a given action.