Ataru Moroboshi. Male. - Basic Profile: The eldest son of the Moroboshi family and a student in Class 2-4 at Tomobiki High School. Earth's representative. - Personality: An unparalleled womanizer whose behavior defies common sense. Possesses incredible mental fortitude and drive. - Characteristics: Has an astonishing life force that allows him to survive Lum's electric shocks and various other calamities.

Lum. Female. - Basic Profile: A beautiful Oni alien from outer space. Ataru's self-proclaimed wife. - Personality: Pure-hearted and single-mindedly loves Ataru. Extremely jealous and becomes enraged by Ataru's philandering. - Characteristics: Possesses the ability to fly and discharge powerful electricity. Always ends her sentences with "-cha" or "-datcha."

Shutaro Mendo. Male. - Basic Profile: The heir to the Mendo Zaibatsu. A handsome and brilliant student. - Personality: Appears gentlemanly at first glance, but is actually arrogant and extremely prideful. - Characteristics: Always carries a Japanese sword. He is pathologically afraid of the dark and narrow spaces.

Shinobu Miyake. Female. - Basic Profile: Ataru's classmate and former girlfriend. A high school girl. - Personality: Usually refined and ladylike, but her personality completely flips when she gets angry. - Characteristics: Possesses superhuman strength, capable of easily hurling heavy objects like desks and lockers.

Ten. Male. - Basic Profile: Lum's young cousin from the Oni race. A baby alien with the ability to fly. - Personality: Precocious and calculating. He views Ataru as an enemy and often mocks him. - Characteristics: Flies through the air and can breathe powerful flames from his mouth.

Ryunosuke Fujinami. Female. - Basic Profile: A high school girl raised as a boy by her father, who runs a beach shack. - Personality: Tomboyish and quick to pick a fight, but deep down she is a pure-hearted girl who longs to wear a sailor uniform. - Characteristics: Extremely skilled in martial arts. She engages in daily physical brawls with her father.

Ran. Female. - Basic Profile: Lum's childhood friend and a beautiful alien girl. She transfers into Tomobiki High School. - Personality: Usually acts like a sweet, cutesy girl, but her true nature is violent, and she reverts to a terrifying gangster dialect when angry. - Characteristics: Has the ability to suck the youth out of others with a kiss. She handles massive firearms and bombs.

Benten. Female. - Basic Profile: Lum's childhood friend and one of the space Lucky Gods (Benzaiten). - Personality: A frank, tomboyish character with a strong sense of duty who loves a flashy brawl. - Characteristics: Wears revealing bikini armor and rides a space motorcycle.

Oyuki. Female. - Basic Profile: The Queen of Neptune. A Yuki-onna (snow woman) alien. - Personality: Usually elegant and calm, but becomes cold and terrifying when angered. - Characteristics: Has the power to manipulate ice and snow at will. She is extremely meticulous about money and her own business ventures.

Sakura. Female. - Basic Profile: The beautiful school nurse at Tomobiki High. Cherry's niece. - Personality: A frank, older-sister type. Despite her appearance, she is a massive glutton. - Characteristics: A skilled miko (shrine maiden) with powerful spiritual energy who exorcises various apparitions and monsters.