Naruto : Gamer System - Chapter 28 : Reminiscing the Past

Humanity was on the brink of destruction. Muyoung, an assassin from the Forest of Death, fell to his knees. There were corpses all around him. For years, he had worked for the Forest of Death and had finally been able to eradicate them. Now, he, himself, was about to die. He closed his eyes as he felt his heart stop beating.

~She is a waste daughter from the Su family that couldn’t cultivate. On the day before her wedding, the Third Prince breaks off their engagement in the street. Her own sister replaces her in the marriage to the Third Prince. She became the center of gossiping in the city. In her resentment, she hits herself on the Su Family’s gate, only to become the object of other people’s ghost marriage.

She, Su Zimo, open her eyes to find herself sleeping in a coffin. It’s not to surprising seeing as she put herself here (hit head on gate), but why is there another person lying beside her? And whats more they are wearing red wedding clothes. After taking all this in she almost faints.

~He, is a cursed person with an indescribable status. This curse that has been passed down in his family for centuries is now effecting him.

A mistaken ghost marriage, a battle in business, and a long period of painstaking love, made their fate intertwined.

- Description from Novelupdates

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.