[[Noshiko Yukimura|Noshiko]]'s tails are represented in the physical world by small daggers called kaiken. In order to sacrifice a tail to summon an [[Oni]], she must break the blade. The older the tail, the more powerful the [[Oni]].

It is not clear at this time whether all kitsune will get kaiken, or how the blades come into existence.

Reference Image

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