Kako

One of the characters introduced in this story is a gigantic tiger that can speak, commonly known as Kako. This aberration is extremely powerful, possessing strength that overwhelms even Tsubasa Hanekawa, whose expertise makes even specialists wary of approaching her. Kako is fueled by feelings of jealousy, turning those emotions into "fire" that can instantly consume and burn down the homes or dwellings of those who are envied. Additionally, Kako is able to instantly move to the intended target before setting them ablaze.

The existence of Kako originated when Tsubasa Hanekawa separated her own hidden feelings of jealousy from herself, thereby giving rise to the aberration. Tsubasa speculated that this aberration is a new kind of apparition based on the Chinese proverb, “Tyrannical government is fiercer than a tiger,” as mentioned in the Book of Rites. However, Shinobu suspects it may actually be based on an existing apparition known as the "Kasha" (a supernatural entity linked to fire). This aberration is thought to be formed not only from jealousy but also from the overall darkness within the human heart.