Heika Watashi wo Wasurete Kudasai

Lunia was a noble lady who lived a lonely life after being rejected by her father and used by her half-brother. One day, her life changed when a priest was chosen to marry Hades. Hades, Duke of Khronoa, who was cursed with death, if he does not marry a woman chosen by the emperor, he will die young. Although Hades said he didn’t love her and he was doing this to break that curse. 

Hades spent a night with her and then disappeared without a trace. After years, he came to know that she was pregnant with her child, and now he went out in search of Lunia and his child.