Patriarch is Taking Concubines Again! - Chapter 62:

Yeon-woo had a twin brother who disappeared five years ago. One day, a pocket watch left by his brother returned to his possession. Inside, he found a hidden diary in which was recorded “By the time you hear this, I guess I will be already dead….”

Obelisk, the Tower of the Sun God, a world where several universes and dimensions intersect. In this world, his brother had fallen victim to betrayal while climbing up the tower. After learning the truth, Yeon-woo decided to climb the tower along with his brother’s diary.

“From now on, I am Jeong-woo Cha.”

It’s said that the prince of virtue had almighty martial arts. It’s said that the prince of virtue had the most handsome appearance in the world. It’s said that the prince of virtue was brilliant. But all was legend! A fire ruined his wonderful appearance and his legs. Even the talented bride under their marriage agreement were replaced furtively. Ye Liu-li was his bad-luck substitutive princess. She went a long way to graduate from Medical University and had her internship with pain and joy. Who knew that in order to save a suicide patient, she fell off the building and crossed time into a “chessman” of prime minister. She had also been married to the disabled prince replacing her elder sister. On the wedding night, when most other couples were having their romantic night, she was thrilled. It didn’t matter. Revenge never came too late. She would never let go of any of them who entrapped her or harmed her.

- 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.

In her third year living in this steampunk world, Ciel gained the ability to simulate both the past and the future.These simulations turned into a game where she could act without restraint, and after countless trials, real life became a replica she could navigate as though speedrunning it.Churches, potions, mutations, the Old Gods, witches, sealed artifacts… none of these have anything to do with Ciel. She’s just an ordinary girl who wishes for a peaceful life.She just happens to be particularly skilled at snuffing out danger before it even begins.