Kururu serves as the head of communications in the Keroro Platoon. Despite holding a higher rank than Keroro, he isn't the leader because of his unpleasant and unnerving personality, earning him the nickname "Yellow Devil." His blood type is AB, fitting the Japanese theory of personality associated with this blood type. His name originates from the Japanese word "kurukuru," meaning "round and round," referring to the spiral patterns on his glasses.
A Sergeant Major in the Keron Army, Kururu is known as the brain of the Keroro Platoon. He is mischievous, deceitful, and often described as evil and enigmatic, almost to the point of being considered a mad scientist. Generally disliked by everyone, most characters see him as a depressing jerk, and action figures of him tend to sell poorly on Keron, much to his chagrin, though he takes pride in his bad attitude.
Despite his general unpopularity, Kururu gets along well with Mutsumi and Aki Hinata. He and Giroro have a strong dislike for each other due to their vast differences—brain versus brawn—and Kururu frequently uses Giroro as a test subject for his inventions.
In his childhood, Kururu was blue. His love for curry turned him yellow. By the third season, Kururu seems to develop a crush on Giroro, much to the corporal's horror. He blushes whenever Giroro pays extra attention to him and wastes no opportunity to woo Giroro through gifts or twisted inventions. Whether this affection is genuine or just another way to torment Giroro remains unclear.
Kururu, being the least emotional member of the Keroro Platoon, is almost never seen crying or smiling, although he rarely panics when things go wrong, likely due to his numerous dangerous inventions desensitizing him.
