I Have Yet to Become a Doll Today - Chapter 810: The Changes in the Stone Chamber

Elijah is dying.Afflicted with terminal cancer, his days are limited. So, after deciding to spend his remaining time with family, he boards a plane and sets off for the Pacific Northwest to be with his sister. However, along the way, Earth is transformed by the touch of the World Tree, injecting it with magical Ethera and connecting it to a much larger universe via the System. More importantly for Elijah, though, it also causes his plane to crash, stranding him on a deserted island. But all is not lost, and through the System, he gains the Druid archetype that may be enough to allow him to survive a hostile environment filled with powerful monsters as well as more mundane threats like starvation and the elements. Meanwhile, his sister, Alyssa, must survive the collapse of civilization as she knows it while trying to keep her family safe. Follow them as they try to navigate an apocalyptic world full of game-like stats, classes, and threats aplenty.

The Immortal Path led to Longevity and Sovereign was heading in ease. When the Longevity was no longer in ease, all living beings were just prisoners. Conspiracy, internal strife, and the invasion of the others, all of it emerged together. 

In such a world, there was such a young man. He made his way upstream, stepping on blood, defying the emperor, destroying the various kings, and slaughtering his way through the hundred clans to form an Immortal Path towards the throne of Sovereign! The Immortal Path was endless, while the Sovereign was limited. He used his blood to forge his immortal legend.

- Description from Novelupdates

He became the villain in the possessed game, the rival of the main character, and the second seat.

Side story of Kyoukai Senjou no Horizon bundled with the first press release of the 1st, 3rd, 5th and 7th Blu-ray volumes of both seasons of anime.

This side story follows Asama, Kimi and Mitotsudaira aboard Musashi one year before the beginning of the main story, as Asama is considering to create a music band together with her two friends for the next festival in Aki, a territory under the governance of K.P.A. Italia.