Kakera (カケラ?, lit. "fragment(s)") is a particular concept among "Voyager" witches. In the When They Cry series they are prisms that represent infinite parallel worlds with different possibilities. The different decisions taken by the characters, circumstances, environment and various other variables pave way for the story to play out in particular ways in different kakera. It metaphorically embodies the idea that reality is a microcosm of innumerable known and unknown factors. In the Higurashi no Naku Koro ni Minagoroshi-hen manga, Bernkastel refers to them as books and gives them different names. Likewise, all of the games in Umineko no Naku Koro ni are given different names. The games themselves can be considered parallel worlds existing at the same time in some sense. These different worlds can be viewed in the Meta-World and in the sea of fragments. In Higurashi no Naku Koro ni, Rika Furude is able to view the different worlds in the sea of fragments. Bernkastel has been shown to have entered the sea of fragments to view the different worlds in order to solve the epitaph. Battler, with a push from Virgilia, discovered the ability to access and utilize the sea of fragments to discover the "truth" in End of the Golden Witch. Aside from being used as a way to view different worlds, Bernkastel has also stated in the same arc that she can make a fragment a reality and in Twilight of the Golden Witch, it was used as some sort of teleporting device by Lambdadelta, which allows Voyager witches such as herself to enter and exit different game boards.

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