A Barrier (結界 Kekkai) is something that separates two spaces, preventing free movement between the two sides, or access to one side from the other. In the Len'en Project, barriers are more conceptual and are, according to Tenkai Zuifeng, "impossible for humans to fully understand".
Setting a Barrier Up
According to Tenkai, most barriers are inscribed on the underside of regular space, giving the "front" and "back" sides separated by the barrier. However, the barrier does not physically exist, thus there is only "front" and "back", and the differing phenomena on each side, nothing in between.
According to Tenkai, barriers have no thickness and mass and can be said to not exist in this world, and thus are "unreal". Barriers do not exist as physical objects, and yet are able to physically separate two areas, as shown by the barrier around the Summonsing Fortress, which only allows entry from the fortress gate.
Uses of Barriers
- As shown by the Summonsing Fortress barrier and the Mugenri Barrier, a barrier can be used to physically separate two areas, despite not being a physical object.
- A barrier can be set up within speech, as shown by Tenkai, what this does is unclear.
- A barrier can be made synchronized with one's memories, allowing one to recall certain information by looking at it, shown by Tenkai.
- A barrier can be used to throw others off course, as shown by those within the Dragonfly Castle.
The Mugenri Barrier
The Mugenri Barrier is a double-layered barrier that separates Mugenri and the Outside World, according to Tenkai and Yabusame, instead of "inside" and "outside", it is more accurate to describe it as "front" and "back".
According to Tenkai, dimensions are separated by barriers as well, called the "dimensional layers". They are what shapes the boundaries of "possibility" within a dimension. According to Yabusame, they taste like tartar sauce, which is confirmed by Tenkai.