Kurourushi/Synopsis

History
Kurourushi is a cockroach cursed spirit born from humanity's fear towards cockroaches and one of the sixteen registered special grade cursed spirits. It was captured and summoned by Kenjaku using Suguru Geto's Cursed Spirit Manipulation technique to participate in the Culling Game.

Culling Game Arc
By November 12th, 2018, Kurourushi had managed to gain 54 points in the Sendai Colony. It was one of the four players locked in a tense deadlock. Due to Dhruv Lakdawalla's technique making him a particularly difficult opponent for Kurourushi, the cursed spirit decided to lie dormant until the ancient sorcerer is killed. Before going dormant, Kurourushi reproduced through parthenogenesis, creating a child.

When Dhruv was killed by Yuta Okkotsu, the cursed spirit awakened and found itself starving. In order to feed itself, it sent out a swarm of cockroaches after civilians trapped in the colony. A man escaped from the cockroaches to a stadium, which formerly belonged to Dhruv and had been recently claimed by Yuta. Yuta saw the man and attempted to rescue him, though his efforts were in vain as the man's lower body was completely consumed after being submerged in the cockroach swarm. The cockroaches quickly consumed the rest of his body save for his bones and subsequently attacked Yuta, who blocked them with his katana. Another wave of cockroaches pursued the civilians that Yuta just rescued, causing the special grade sorcerer to summon his cursed spirit to knock down a bridge and block the cockroaches. Yuta then destroyed the remaining cockroaches by outputting a large amount of cursed energy into his sword swing.

With its cockroaches killed, Kurourushi appeared near Yuta to directly confront him, instinctively targeting him due to the sorcerer interrupting its meal. Noting Kurourushi's indiscriminate attack on people, Yuta resolved to exorcise the curse to prevent it from leaving the colony's barrier in case the rule that allows travel between colonies is ever made. As Yuta readies himself, Kurourushi drew its Festering Life Sword, an enchanted blade that mixes life and death.

The two special grades proceeded to engage in combat, with Yuta initially overwhelming the cursed spirit with his strength and speed, and dealing considerable damage to it. Kurourushi then put some distance between them by hovering on a tornado of cockroaches. After Yuta noted that two players with high scores were watching him and decided to not use Rika or Reverse Cursed Technique to exorcise Kurourushi, the cockroach curse asked why Yuta was interfering with it. Yuta turned the question around and asked the curse why it was killing humans, to which it responded that it liked the taste of iron.

The curse then chanted "blinding" thrice before using Earthen Insect Trance to conjure two small flying curses that carried large nutshell-like pouches between their legs. It then sent a swarm of cockroaches to surround Yuta, who repelled them by stabbing his katana in the water and creating a cyclone of water around himself. As the cockroaches fell around him, the two flying curses approached him, causing the sorcerer to slice them apart with his sword. However, it is revealed that the pouches contained a liquid that was able to temporarily impair Yuta's vision when splashed onto his face, allowing Kurourushi the opportunity to approach Yuta.

Kurourushi and Yuta clashed weapons, the Festering Life Sword shot small egg-like projectiles into Yuta's shoulder, forcing him away. The eggs immediately hatched and spawned small insect-like curses from the wound, injuring Yuta and distracting enough to allow Kurourushi to land a second hit directly on his abdomen, which spawned more curses and greatly injured the sorcerer, seemingly defeating him.

Just as Kurourushi prepared to devour Yuta, he suddenly pulled in Kurourushi by the face and delivered a mouth-to-mouth blast of positive energy using Reverse Cursed Technique. As Kurourushi is a cursed spirit comprised entirely of cursed energy, the positive energy compromised and disintegrated its body, leading to its exorcism. With Kurourushi's death, Yuta gained five points. After Kurourushi was exorcised, the cursed energy from Japan's persisting fear towards cockroaches transferred to its child, allowing Kurourushi to be reborn.

When Ryu, Takako, and Yuta expanded their domains at the same time, Kurourushi invaded the domain clash while distracting Rika with its cockroaches outside of the domains' barriers. Its unexpected intrusion in addition to the three Domain Expansions' differing internal and external conditions when constructing their barriers caused the barriers to collapse simultaneously, ending the techniques of all three sorcerers.

After Takako was kicked near Kurourushi by Yuta, the cursed spirit charged the sorcerer and struck her arm with its Festering Life Blade, severing it. Taking advantage of Takako's injured state, Ryu blasted her with his Granite Blast, incapacitating her and severely damaging the left side of Kurourushi's body due to it being nearby. Yuta then casually grabbed the cursed spirit's head and exorcised it once more with Reverse Cursed Technique.