The Demon's Menu - Chapter 652: People Always Have Times of Obsession

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.

The Overlord, Kang Chul-In. The man who was so strong that he had to be defeated. Having lost, he must now go back in time to take up the challenge of becoming The Emperor in the Continent of Pangaea. Will Kang Chul-In be able to overcome the 9 other Overlords in order to grasp the Continent of Pangaea within his hands?

…but it seems pretty doable.