Renkin San-kyuu Magical Pokaan is a slice of life anime series centered on four princesses from the Underworld who have decided to live in the human world inside a large treehouse. There is very little plot in the series as it mostly focuses on the daily lives of the princesses and how they adapt to life in the human world. The narrator is actually the fifth princess who doesn't make an appearance in the show because she is invisible.
- A cheerful and happy girl, Uma is a witch who is quite bad at casting spells yet is fascinated with the human world. She is reminiscent of a rabbit, with her ear-like hairstyle and strange bunnies she keeps as pets, but she is the least monstrous of the group. Uma's skirt tends to lift up when she is casting spells, providing the viewers with many panty shots whether they like it or not.
- As a werewolf, you'd think Liru would transform into a fearsome beast when the moon is full. However, this is an anime about cute girls, so she transforms into a cute little puppy. Liru is very energetic and is commonly engaged in dog-like behaviour such as splashing through mud puddles and rolling around on the ground. She has large dog ears and a fluffy tail but looks very human otherwise.
- Wearing sunscreen is enough to protect Pachira from sunlight, as shown in the beach episode, even though she is a vampire. She is seen drinking tomato juice often, and seems to gain sustenance from it rather than blood. As a vampire she isn't very frightening, with her hair tied into twin tails with small bats as ribbons. Pachira's main shortcoming is her bust, according to her.
- Despite her wish to become human, Aiko is confined to a heavy and cold metal body with an old processor and too little memory. She's as gentle as she can be as an android but will often break things due to her extreme weight. Aiko cooks, shops for groceries, and does the laundry for the other girls. She is very devoted and not scary at all even with her metal hands and feet.
- The only minor character of note, "Super" Doctor K-Ko is a ridiculously busty scientist who tries her hardest to prove that the monster princesses are truly terrible and fearsome monsters to the scientific community. In spite of her efforts, humanity is mostly indifferent to the girls.