Kyoukai Senjou no Horizon - Volume 1B, Chapter 21: Worrier in the Twilight

Sirens: a name derived from an ancient creature, used to describe those who could charm, lure, control, and heal others by singing.

Subjected to live the life of a siren, Aria had experienced, seen, and heard many horrific things. Broken beyond repair, Aria resigned herself to death, when suddenly…

The Grand Duke, Lloyd Cardence Valentine, arrived and whispered, “Should I kill everyone here?”

“If you need me, just call me. Your song will always reach me, wherever you are.”

In the end, Aria called the devil, bringing death to all those present, along with herself.

“Let’s fall down to hell together.”

And with that, Aria breathed her last and died… only to return to her 10-year-old self.

Now that she had a second chance at her life, Aria was determined to change her fate, as well as the cruel fate of her saviour, Grand Duke Valentine.

And so… Aria proposed to him with a marriage contract.

She sold her soul to the devil and vowed to protect him.

The young duke took the contract from her hand.

“So, where should I stamp the seal?”

* * *

“You said you’d divorce me within 10 years.”

The grown-up villain leaned in, hovering his head before he kissed her tenderly over her crown.

“Now that we’re adults, we should sign another contract.”

Super soldier Su Chen, returned to the city and returned to the city, set off all directions! The king of soldiers that once famous the world, let everyone be convinced!

- Description from xbiquge

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.

“Please, I implore you to save the world.” This is what a goddess in white says to me in a pure-white space. Such is the standard line that suggests the game is about to begin. Please say this stirring line to boys and girls with sparkling eyes! It’s wrong to direct it to someone like me, who’s exhausted from job hunting! When I declined her politely, she flew into a fit of tears; when I agreed to assist her on small tasks out of reflex, she proclaimed: “it’ll be fine if you just help in the Starting-Village Arc. Please guide the Hero!” Then she tossed me into another world. No, this is a world modeled after a game that this gamer goddess likes…