- For the game created by Deep-Sea Prisoner, see Mogeko Castle.
- "Once, there was a lonely individual. Unable to bear his solitude, he made a kingdom solely for himself. He became the king of the land... A kingdom needs a castle for its king... So the king made one right in the center. This is that castle... but there was nothing inside the castle. It was just a world of nothingness. The king pondered. And he made seven Mogekos. Those were... the special Mogekos. They were put on each floor, to serve as that floor's guardian. Then the king made many more Mogekos, and the land became much busier. The king looked upon it, and was very satisfied. That was the genesis of Mogeko Castle."
– Defect Mogeko
In the past some parasites got into the castle's prosciutto, infecting and wiping out 70% of the Mogeko population.
Sometime before the events of Mogeko Castle, King mogeko ordered Defect Mogeko, then known as Nega–Mogeko, to be executed for questioning his doctrine. Following Defect Mogeko being the first to be labelled as 'defective', after him every Mogeko who posed a danger to King mogeko's doctrine would be labelled "defective" and "a danger to the Mogeko kingdom" and subsequently executed.
In Mogeko Castle
The castle serves to be the main obstruction between Yonaka and her brother, and the majority of the game is about Yonaka ascending the floors of the castle in order to reach the top, where she may return home from.
The castle´s walls are surrounded by a forest, and is somewhere near an 'abandoned' train station by the name of Mogeko Station, the station that the route of the Mysterious Train ends at. It resembles a stereotypical European castle, with various conical towers at its walls and a tall tower in the center of the castle, whose roof is shaped like a Mogeko head.
InteriorThe castle has seven floors, each with its own guardian, collectively known as the Special Mogekos. Some rooms aren't rooms at all, but in fact, "realms". Defect Mogeko mentions the castle having "infinite space" and always "expanding and extracting". Throughout the castle, absurd amounts of prosciutto and pornography can be found littered on the ground.
The guardian of the first floor is Somewhat Strange Mogeko. The floor is the first floor Yonaka finds herself on upon entering the castle. The floor has a large foyer, of which a large portrait of a Mogeko is hung.
To the left of the castle's entrance is a cafeteria, where all Mogekos go to eat. Connected to the cafeteria are two rooms filled with boxes, and two kitchens.
The Mad Room is a disturbing pitch-black room, floor covered with blood. In the air distorted Mogekos float in the air, and the only Mogekos to be found in the room are Mad Mogekos covered in blood.
Somewhat Strange Mogeko's Room
The floor guardian, Somewhat Strange Mogeko, has his own room. The room has two couches centered around a square table. The floor is covered with stray sheets of paper(a receipt for a porn magazine, a poem written by Somewhat Strange Mogeko, and a piece of paper with "Prosciutto vs. Pancetta ~Clash of the Gods~), and in the top left corner are three shelves. The shelves are filled to the brim with porn.
The guardian of the second floor is Prosciutto Fairy. The floor contains a large amount of Mogeko larvae and is somewhat bright in comparison to the other floors from the castle.
The guardian of the third floor is Blood Spirit.
The third floor appears to house a prison of sorts, a prison that Defect Mogeko was imprisoned in, a prison that would later imprison Yonaka.
The third floor is the last floor accessible through stairs.
The guardian of the fourth floor was Hasu, until the day he was usurped from his position by Moge-ko. Currently, the 'guardian' of the fourth floor is the aforementioned Moge-ko.
The Mogekos in this floor were described by Yonaka as being somewhat sad and downtrodden, likely due to the influence of the floor's new 'guardian' Moge-ko.
The guardian of the fifth floor is Moffuru. The floor is inhabited by fluffy Mogeko-like creatures called Mofukos, who are in truth Mogekos that have been infected by lethal Blancfluff Mogeparasites, that are highly contagious parasites that affects normal Mogekos. Normal Mogekos do not inhabit the fifth floor nor are there any visitors to the floor aside from Special Mogekos, as the floor is used as a quarantine for those afflicted with the disease and awaiting execution by monster devouring. Dead Mofuko souls fall from the sky in the fifth floor.
Located on the fifth floor is a hospital for Mogekos. The hospital houses many sick Mogekos, many of whom are convalescing from hay fever. The hospital also houses a weapons room, full of a variety of weapons.
The Fluff Path is where the souls of dead Mofuko become stars, which fall on the land. In the sky, the aforementioned Mofuko souls can be seen cascading down to the ground. At the end of the path is Lord Prosciutto's light, which can be used to ascend to the sixth floor.
The guardian of the sixth floor is Mogecuckoo.
The sixth floor houses King mogeko's throne room. It also contains a gigantic library, and a room that resembles the first floor of the castle.
The guardian of the seventh floor was Nega-Mogeko prior his imprisonment. It was said by Somewhat Strange Mogeko (and, later, confirmed by Defect Mogeko) that it has a door that might allow Yonaka to return to the Human World.
- Mogeko Castle - The castle served as the main setting for the majority of the game.
- Four Obsolete Dream characters make cameo appearances within the castle: Kurotsuno appears on the second and fourth floors looking for her phone, and on the fifth with Hanten and Met once her phone has been found. Hanten and Met appear on the fourth, looking for Kurotsuno, then the fifth with Kurotsuno after she recovers her lost phone. Sullivan makes an indirect cameo, in the form of a letter addressed to Olivia.
- On the first floor, Yosafire and Wadanohara make a cameo in the form of miniature figurines on the top of Somewhat Strange Mogeko's shelf.