The Interface World (界面世界, Kaimen Sekai) is a parallel world to that of the Boogiepop Series, which, inside of the Interface World, is called The Other Side of the Water (水面のむこうがわ, Suimen no Mukōgawa). It is primarily detailed in the Jiken Series.

Compared to the Other Side, the Interface World is very different, as there are no MPLS, but instead Magic, as well as Dragons and other fantastical elements. However, as there exists a pair of Witches in the Interface World as well (Bias Li Carz and Oris Quart), it is possible that the existence of such a pair is a constant in all alternate worlds.

Interface Interferometry

Interface Interferometry (界面干渉学, Kaimen Kanshōgaku) is the study of interaction between worlds. A few objects, such as pistols, scissors, crosses or even cars, from the Other Side sometimes travel to the Interface World. Other objects that occasionally show up are books by Seiichi Kirima, who ended up being named The Truth within the Fog.

While only these few objects have traveled from the Other Side to the Interface World, multiple people and creatures have traveled from the Interface World to the Other Side (seen in Beyond the Dragon's Skies). Examples include Kunio Koryou, whose earliest memory was being inside a blood-red room as a baby, in a place far, far away. He was imparted with a magical seal that protects him from any and all danger, and sent to the Other Side, where he was discovered underground.

Related Terms


This is a list of characters originating in the Interface World:


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