The Reincarnated Extra - Chapter 436: "Humanity"

There was a man in the modern world that built his business empire from scratch. He was hailed as a genius by his peers and was respected worldwide due to his contributions to the world.If it is not only for that unfortunate accident that led to his death. He was a man who could potentially change the world with his mind that still stores a plethora of ideas.But—fate had others plan with him. He found himself in another world, what’s more, it’s primitive and technologically backwards compared to his last world. And what’s more, he turned into his younger self, and in this world, he was an orphaned boy.For him to survive, he must use everything that he had at his disposal, and that was all in his head.

After assisting the man she loves with all her heart to the throne, Li Wanrou dies miserably in the cold palace, her dead body wrapped in a broken mat and thrown into the disorderly funeral hillock.

A good-for-nothing man married a beautiful girl but was kicked off the bed on the wedding night. Furiously, he wrote a bill of divorce and ran away.
He was schemed a car accident in which he nearly lost his life. However, it turned out to be a blessing. He swallowed the soul that passed through the outer world, thus obtained superb medical skills and martial arts.
Later on, with the silver needles and invincible martial arts, he embarked on the road of counterattacks and was committed to his great dreams.

- 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.