Waking up as Diavolo in 1987, and seeing the domineering Crimson King before him, Diavolo refuses to be trapped in an endless cycle of death.
The otaku died of a terminal illness and took over the body of Kokushibo from the Demon Slayer world.
In order to survive and make up for some of the regrets he had when watching the anime, he decided to become Kokushibo and live in this world...