"Ane no Spare" to Yobareta Migawari Jinsei wa, Kyou de Yameru Koto ni Shimasu ~Henkyou de Jiyuu wo Mankitsu Chuu na no de, Imasara Shin no Seijo to Iwarete mo Shirimasen!~

Because they possess rare healing magic, twins Mocha and Karina are appointed as Saints of the Royal Palace. However, the older sister, Karina, suddenly abandons her duties, forcing the younger sister, Mocha, to shoulder both of their workloads and spend her days working herself to the bone.

One day, after having all her hard-earned achievements stolen by Karina, Mocha is told that 'the sister's spare is no longer needed.' She is then forced into a political marriage with Margrave Alexis Veliky, the commander of a cursed order of knights.

However, Mocha is actually overjoyed, thinking, 'I'm finally free from all that grueling work!' Her heart fluttering at the dawn of a brand-new life, she sets off for the Margrave's territory in high spirits.

But waiting for Mocha in this frontier land plagued by dark rumors is Alexis—a Knight Commander with a complicated past who views Saints as his absolute sworn enemies...?