Wrath, formerly known as Sasajima Kyouya, was a Japanese high school student who died in a classroom explosion. He reincarnated into a new world as a low-level goblin. Initially finding contentment in his goblin tribe's primitive hunter-gatherer existence—a stark contrast to his dissatisfaction with modern society in his past life—this relative peace shattered when humans annihilated his village and enslaved him.

Severe abuse during his enslavement triggered his unique skill, "Wrath." This ability multiplied his combat power tenfold but at the severe cost of his sanity. Consumed by the skill, he broke free and embarked on a violent rampage, evolving from a goblin into an oni. His uncontrollable rage only ceased when Shiraori defeated him and forcibly deactivated the skill. Following this, he aligned himself with Shiraori and her companions, including the Demon Lord Ariel.

Within Ariel's faction, Wrath rose to command the 8th Demon Army, operating under her authority to advance their objectives. His relationship with Shiraori remains shaped by her subduing him. He retains connections to his human past, notably a prior friendship with Schlain (Shun) from their Japanese school days. Their moral frameworks frequently clash, reflecting divergent perspectives forged by Wrath's traumatic struggles versus Schlain's sheltered upbringing.

The "Wrath" skill remains central to his identity, symbolizing both his traumatic past and formidable combat role. His journey illustrates adaptation to extreme circumstances, moving from enslavement to martial authority while navigating complex loyalties and the psychological weight of his abilities.