Ebi is a rare and mysterious magical creature originating from the world of Seiren. In the anime adaptation, Ebi is accidentally brought to Earth hidden inside the luggage of the Seiren resident Tomoka Lana Jude. After arriving, she is adopted as a family pet by Miharu Sena Kanaka and the Sasaki household. Her species is officially unknown, but she is described as a lifeform that inhabits Seiren. Ebi's physical appearance is a unique and somewhat ambiguous combination of features. She is a small, plump creature about fifty centimeters in length and weighing around five kilograms, bearing a resemblance to a miniature seal or perhaps a small dog or cat. Her face has feline characteristics, and she possesses a pair of large, bobbing antennae on her head. Her tail is shaped in a way that reminded Miharu of a fried shrimp, which directly led to her name, as "Ebi" is the Japanese word for shrimp. Her gender is implied to be female.

Despite having a very limited vocabulary and being unable to speak human languages, only able to vocalize sounds like "nyaa," Ebi demonstrates surprising intelligence. On one occasion, she was shown to be capable of complex strategic thought, mentally planning out an entire game of Mahjong. However, her inability to communicate these plans to her novice teammate rendered her efforts useless. Her role in the story is primarily that of a pet and a source of comic relief, often finding herself at the mercy of the other characters' antics. A notable aspect of her personality is her seemingly endless curiosity, which often manifests as a habit of putting things into her mouth, similar to her owner, Miharu. She has a great deal of innocence and suffers much of her torment without any real malice from those around her.

Ebi's most significant relationship is with Tomoka Lana Jude, the girl who inadvertently brought her to Earth. Tomoka has a habit of using Ebi for various rough and unconventional purposes, such as swinging her like a flail, using her as fishing bait, or throwing her like a handball. Despite this treatment, Tomoka is also shown to possess magical knowledge, including the ability to temporarily transform Ebi. On one occasion, Tomoka used this skill to turn Ebi into a small girl with short green hair and green eyes. In this form, she appeared as a human child. Ebi also lives under the care of Miharu, who named her and considers her a pet. While Miharu initially wondered if Ebi would be edible, this thought passed, and she became a member of the household.

Ebi possesses several notable abilities that set her apart from a typical pet. Her most prominent power is the ability to fire a powerful energy beam from her mouth. This attack is referred to by Tomoka as the "E-beam." She is also capable of locomotion despite having no visible legs, moving by either floating in the air or hopping about. In addition to her beam attack, she has been shown to transform into a human girl under specific magical circumstances, such as when Tomoka uses her powers. While she endures a fair amount of slapstick torment, particularly at the hands of Tomoka, she remains a resilient and enduring presence within the group.