There exists an underworld where four princesses from the underworld known as the "Netherworld" exist. They are Uma the Witch, Pachira the Vampire, Liru the Werewolf, and Aiko the Android.

These princesses found their way to the human world after chasing down Super Doctor K-Ko and are adapting to life in the human world. They reside in their Garakuta House, which is just a makeshift treehouse.

The girls are faced with small self-centred problems such as finding a boyfriend, blending into society, learning about Earth's cultures, and staying one step ahead of Super Doctor K-Ko.

Uma is a witch, although she is not yet adept at spell casting due to her being a "third rate alchemist." She has a happy personality and finds joy in exploring the human world. When she discovers the world, she quickly and proudly points it out to the other girls only to be generally the last to discover such things, becoming disappointed when others learn faster than she does. When she is not trying to master spells, Uma reads romance manga. Sometimes when Uma is casting a spell, her skirt lifts revealing her panties. Her overall design is reminiscent of a rabbit-girl ranging from her hairstyle that occasionally moves, her pet rabbit like creatures, and the carrot cushion that she sleeps with.

Pachira is a vampire with pointy ears and two small black bats riding on her hair ribbons. She displays the common weakness of vampires such as a weakness to garlic and holy water. However, her biggest weakness...at least in her mind, is her small breast size which she hopes to have expanded in whatever way possible. She has the ability to fly by sprouting wings, extends her fingernails into claws, and is seen eating regular food as well as having a vampire's traditional lust for drinking blood...although she mainly drinks tomato juice. She turns to ash in sunlight, but it is not fatal as she just ends up in a burnt state. Pachira wears a long coat and a cardboard box over her head whenever she goes out. When she goes to the beach, Pachira wears a heavy coat of sunscreen on her skin to prevent her from getting burned. Though Pachira wouldn't show up on any camera due to her not casting a reflection, she can be seen on a thermographic camera.

Liru is a werewolf with her wolflike ears and tail exposed in her normal form. She appears as a tan blonde haired woman dressed in a brown leather harness that goes across her breasts, brown fingerless gloves with gold-spiked bracelets on them, blue denim shorts, and white thigh length boots. Liru has an energetic personality and has animal traits such as the ability to leap great distances with little effort, and has enhanced strength, speed, stamina, and senses. Like all werewolves, she is lycanthropic and her wolf form looks similar to a yellow puppy. Liru is also shown to have a weakness to silver. Being a werewolf, Liru enjoys eating any type of meat and her favourite type of meat is Matsuzaka Beef.

Aiko is an android with silver hands and silver boot shaped feet, an outdated CPU, and low memory size. Her name is a pun of "Aiko. It is a common girl's name, but the "Ai" in her name is written with the kanji for "Iron" rather than "Love." Aiko performs housekeeping duties for the other girls like cooking, shopping, and laundry because of her devoted mind making her the housekeeper of the group. Her weight is 660 lb or more which causes problems since her weight tends to break things, like elevators and ski lifts. Being an android, Aiko does not eat or drink which can come in handy. One time two snow people served cold food that temporarily froze the other three princesses. She always hopes to get her own human type body through whatever way possible. When at the beach, Aiko uses a wind up submarine type suit to go swimming after getting herself waterproofed.