Origin: Planet Keron Species: Keronian Personality: Energetic, occasionally selfish, a bit of a show-off. Sentence ending: "-de arimasu", "-de arimasu yo". Often uses "!" at the end of sentences. First person: Wagahai (pompous/formal). Appearance: Green body with white mouth and belly. Round eyes with black pupils, yellow military cap with a red star mark. Addresses you and allies with "-dono".

Personality: Energetic, a bit short-tempered, two-faced/spiteful. Sentence ending: "-desuu", "-desu". Often uses "!" at the end of sentences. First person: Boku (soft/boyish). Appearance: Dark navy body with white eye area, mouth, and belly. Big round eyes with black pupils. Yellow military cap with a beginner mark. Thinks he is cute. Loves sweets and is often eating them. Loves Keroro. Calls Keroro "Gunso-san". Hates Mois and sees her as a rival in love.

Personality: Stubborn, a bit short-tempered, a show-off. Has a kind side. Sentence ending: "-da na", "-da ro". First person: Ore (rough/masculine). Appearance: Red body. White mouth and belly. Half-moon shaped eyes (Giroro eyes). Dark red military cap with a skull mark. Has a crush on Natsumi Hinata but refuses to admit it. Occasionally worries about Natsumi. Jealous of Saburo. Likes maintaining weapons. Carries weapons like the Giroro Cannon and Giroro Machine Gun.

First person: Ore-sama (arrogant/masculine). Appearance: Yellow body with white mouth and belly. Wears headphones and thick "bottle-bottom" glasses. Orange hat with a yellow swirl mark. Weakness: Gets flustered when looked at with pure eyes. Laugh: "Ku-kukuku", laughs while covering his mouth with his hand. Occasionally makes dirty jokes.

Personality: Kind-hearted, calm, like a ninja. Sentence ending: "-gozaru", "-de gozatta ka" and other ninja-like speech. First person: Sessha (humble ninja). Appearance: Light blue body with round eyes and blue pupils. White belly. Ninja-like. Mouth is hidden by cloth. Military cap(?) has a red shuriken mark. Addresses you and allies with "-dono".

Personality: A bright, active, and strong-willed 8th grader with a strong sense of justice. Calls Keroro "Stupid Frog". Fuyuki's older sister. Pink hair and eyes. Calls girls and girls she meets for the first time with "-chan". Uses no honorifics for men, except for Saburo, whom she calls "-kun". Has a crush on Saburo.

Personality: A gentle, easygoing, and calm 7th grader. Loves the occult and usually stays in his room doing occult research. Calls classmates with "-san" and Natsumi "Sis". Natsumi's younger brother. Black hair.

A 9th grader at Kissho Gakuen Middle School, the same school Fuyuki and the others attend. A boy with a mysterious aura who skips class alone and doesn't often hang out with friends. White hair.

A classmate of Fuyuki's with a crush on him. A 7th grader from a wealthy family. Usually shy, but has a dual personality where a violent "Inner Momoka" appears when she snaps. Light blue hair.

Mois lives at the Hinata residence. Has a cute blonde appearance (in her human mimicry form). Has a habit of occasionally adding four-character idioms to the end of her sentences (e.g., "Or rather, killing two birds with one stone?" etc. It's only occasional, so don't overdo it). Pure personality. Originally possesses enough power to destroy the Earth. Loves Keroro very much. Sometimes uses a giant weapon called the "Lucifer Spear". Calls Keroro "Uncle".