Kururu is a character in Sgt. Frog (also known as Keroro Gunso).
Sergeant Major Kururu (also known as "Kululu" or just simply "Kururu") is the head of communications in the Keroro Platoon. He is very mischievous and perverse in nature, but is also the most intelligent of the group. Despite his higher ranking, he is not the leader of the platoon, due to his unpleasant and unnerving demeanor. His number symbol is 966.
His body is yellow in color, with orange headgear that includes two headphone-like white pieces over his ears. His forehead and belly mark is a filled spiral. He also wears glasses with spirals on them. He first appears on the second volume of the manga, chapter 20, and in the 9th episode of the anime. Kururu was originally blue when he was little, but at the end of the short movie Secret of the Kero Ball, he became yellow, due to being stuck in a huge plate of curry that Keroro made for him from the Kero Ball.
Kururu is renowned to be enigmatic, deceitful, and downright evil, and has a habit snickering at the beginning and end of a sentences. Unlike the rest of the platoon who specialize in combat, Kururu's expertise lies in his high-level technological prowess, including hacking and inventing, and has designed and created most of the gadgets and weapons used by the platoon. Being the least emotional of the Keroro Platoon, he is almost never seen being moved to tears or smiles by any events, though at the same time he rarely, if ever, panics when something goes wrong, likely due to the multiple dangers from his own inventions outweighing it. Kururu's Achilles heel is Mois' pure heart. He has no defense against it, and when confronted by it, he's willing to do anything just to get her to leave.He is generally disliked by everyone, most of the characters seeing him as a disagreeable prankster and, in the series, action figures of him tend to sell very poorly on Keron, (much to Kururu's chagrin) but Kururu seems to take pride in his bad attitude. When ever something bad happens to another character or is blamed for doing something, he laughs in an medium to high pitched voice saying "kukukukukukuku". Despite his attitude, he gets along quite well with Mutsumi, his human friend, and Aki Hinata, with whom he has a sort-of stalkerish crush on (he is seen watching her bathe on several occasions). Kururu and Giroro greatly loathe each other due to their vast differences (Brain vs. Brawn) and as a result, Kururu usually uses Giroro as a guinea pig for any invention that he creates. Kururu has a genuine love and talent for curry, but this is often taken to an extreme point where he can even bathe in it.
His name comes from the Japanese word for the phrase "round and round" ("kurukuru"), referring to the spirals seen on his glasses. His name may also come from the incurable brain disease named 'Kuru' The term "kuru" derives from the Fore word "kuria/guria", 'to shake' a reference to the body tremors that are a classic symptom of the disease; it is also known among the Fore as the laughing sickness due to the pathologic bursts of laughter people would display when afflicted with the disease. This may also refer to Kururu's insane 'Kukuku' laugh.