Sergeant Major Kururu

Rank: Sergeant Major
Color: Yellow
Aliases: 966
Age: unknown (younger than Keroro)
Gender: Male
Species: Keronian
Date of Birth: unknown
Blood Type: AB

Kururu is a Sergeant Major in the Keron Army, and the head of communications in the Keroro Platoon. Although he is of a higher rank than Keroro, he is not the leader of the Platoon due to his unpleasant and unnerving demeanor, which has given him the nickname of 'Yellow Devil'. His blood type is AB, which is befitting his Japanese blood type theory of personality . His name comes from the Japanese word for the phrase "round and round" ("kurukuru"), referring to the spirals seen on his glasses.

Kururu is the brain of the Keroro Platoon, officially in charge of intelligence and planning, and the alien partner of Mutsumi Hojo. However, he is extremely mischievous, deceitful, and downright evil and enigmatic, almost to the point where some people might call him a mad scientist. Despite this, he gets along quite well with Mutsumi and Aki Hinata. 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, and when the platoon and their human friends are having a spooky story competition, Kururu tortures Giroro by hooking him up to the 'fear meter' that measures how scary the story was (using Giroro's own fear).

By the third season however, Kururu seems to have developed a sort of crush on Giroro, much to the corporal's abject horror, blushing whenever Giroro pays extra attention to him, and wasting no opportunity to woo Giroro by way of gift or twisted invention. Whether this affection is genuine, or merely a new way for him to torment Giroro remains a mystery. 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 body color is yellow, though he was originally blue. It is revealed in Chibi Kero: Secret of the Kero Ball!? that he was dyed yellow due to falling in a large plate of curry. His stomach has a red swirly mark on it; a yellow one is also located on his hat, though it is purple in the 114th episode of the anime. Spirals can also be seen on his glasses. When these glasses are removed in one way or another, Kururu often begins to mumble "my glasses, my glasses" and starts searching for his glasses. His headphones have the ability to take the sound a person hates the most and send it into their brain, usually using the antenna located inside of them, and it can also erase other people's memory (surprisingly, this is a very painless process). Kururu also loves curry, but often takes this to the extreme, even seen bathing in it, and can withstand even the spiciest curries.