Kake Mono ni Natta Sobahi

“Loser's concubine" was the title given to Nereis. The Crown Prince broke off his engagement and Nereis became the target of ridicule in the royal palace. She is required to perform her duties as a concubine and to give all the credit to the crown prince who has become king.

Once a year, a gorgeous night when the kings of the two countries bet on a wager, she was taken away as a "prize" by Kval, the king of the neighboring Grannus Empire, and welcomed into the harem.

What does the emperor want, and what does Nereis protect - love, reserve, or trade? The first move is decided by the true feelings that no one can say. The story of the "loser concubine" who was treated as a prize until she was doted on by a cold-blooded emperor.

https://www.cmoa.jp/title/343301/