Sergeant Major Kururu (クルル曹長, Kururu Sōchō), localized as Kululu in Funimation's English anime dub, is the resident genius in the Keroro Platoon. His body is yellow, with orange headgear that includes two headphone-like white pieces over his ears. His forehead and belly mark is a filled spiral. He wears glasses with spirals on them. Kururu was 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 colossal curry plate that Keroro made for him from the Kero Ball.
Although he is the highest-ranking officer in the platoon, he is not the leader due to his unpleasant and threatening demeanor, which has given him the nickname of 'Yellow Devil.'[citation needed] Kururu is enigmatic, deceitful, lazy, sadistic, and has a habit of snickering (with a characteristic "Ku Ku Ku" sound) at the beginning and ending of sentences. Like Keroro, Kururu appears to have little to no interest in conquering the planet, though his disinterest in accomplishing this mission is more out of sheer laziness. Unlike the rest of the platoon who specialize in combat, Kururu's expertise lies in his high-level technological prowess, including hacking and inventing; he has designed and created most of the gadgets and weapons used by the platoon. Many of his inventions that he builds at Keroro's request often end up backfiring. It is heavily implied that Kururu intentionally does this due to his low respect for Keroro's plans and the pleasure it gives him to watch Keroro fail.
He is generally disliked, most of the characters seeing him as a disagreeable prankster. Kururu cares very little of what people think of him and often ignores others attempts to set him straight, being able to ignore just about anyone who tries to talk any sense into him except for Mois, who once inadvertently got him to stop a sadistic string of pranks by simply looking at him with a sad face. Despite his unfriendly personality, Kururu surprisingly becomes cooperative whenever Keroro develops an invasion plan whether or not it involves a personal agenda, often building whatever Keroro requests with little to no reservations despite intentionally sabotaging most of these plans himself.
In the series, action figures tend to sell very poorly on Keron,[10] but Kururu seems to take pride in his bad attitude. Whenever something bad happens to another character or is blamed for doing something, he laughs in a medium- to a high-pitched voice saying "Kekekekekekekeke." Despite his attitude, he gets along quite well with Mutsumi, his human friend, and Aki Hinata, with whom he has a stalkerish crush. Kururu and Giroro greatly loathe each other due to their vast differences (brain vs. brawn).[11] As a result, Kururu usually uses Giroro as a guinea pig for any invention that he creates.
His name comes from the Japanese word for the phrase "round and round" ("kuru kuru"), referring to the spirals seen on his glasses.[citation needed] Her Animal form is Bat.
