"A beauty... So otherworldly it's frightening." For generations, the Kuguu family's daughters have been born with purifying power, acting as shrine maidens for the village. Yuzuki was born into this family as the older sister of twin girls. While possessing purifying powers far greater than that of her sister, Mizuki, she is neglected by her family due to a mark that resembles a dragon on her back, which is seen as an ill fortune. The family conveniently uses Yuzuki's powers to make Mizuki look like a princess shrine maiden, who the villagers deeply admire. Tired of being used as a tool, Yuzuki dreams of her freedom and leaving the family to find the source of the mysterious voice she's heard occasionally since childhood. However, when that dream is crushed and she falls into deep despair, a God of calamity in the form of a huge dragon appears in the sky. Yuzuki is offered as a sacrifice, and she suddenly sees a flashback of her past life. Then, a dragon god, Sogyoku Seotsu, appears in human form and embraces Yuzuki. "I'll never let go of you again... My bride." The true princess shrine maiden is offered as a sacrifice in her younger sister's place and learns of the promise made between the dragon god and his bride in her past life.

"This time, I'll protect my son's life and my happiness...!" The king is killed in a coup, and as his daughter, Lusha grows up locked away in a cell. One day, she is suddenly taken from her cell to be married off to Emperor Ricardo, known as the Cold Blooded Emperor for his terrifying looks and personality, in her cousin Marguerite's place. Lusha soon finds out that it is a marriage in name only and her only duty is to bear an heir. However, when she gives birth to her son, she feels happiness for the first time. Meanwhile, hoping to use Lusha's position and son to her advantage, Marguerite sends an assassin to kill Lusha. Right when Lusha is murdered, she miraculously goes back in time to when she lived in a cell. Determined to avoid being killed herself and saving her son, Lusha marries Ricardo once again. This time around, she notices a surprising side of Ricardo she never knew before... The stand-in princess who was forced into a marriage with the Cold Blooded Emperor and murdered leaps back in time and turns her life around completely!

Summoned to another world as a "bonus" to a saintess, what awaited the heroine was a forced marriage with a poisonous bird emperor?! Rui Kanzaki was transported to another world with her younger twin sister. Her sister, having an aptitude for every kind of magic possible, is treated as a saintess. On the other hand, Rui is treated horribly due to having absolutely no magic ability and only having poison resistance. One day, Rui is married off to the emperor of a neighboring beastfolk nation in her sister's place. The emperor turns out to be a descendant of a poisonous bird clan, whose body brims with lethal toxins. A strategic marriage of a lonely emperor and a stand-in saintess - What will happen now that the lives of two completely different individuals have crossed paths?!

The duchy of Alita was invaded by the monarchy, the Empire of Sckinia, and is now under its rule. The children of the nobility of the former duchy were incorporated into the imperial educational system, where they are given the duty of becoming mates with a partner chosen by the empire in spring when they turn 18, and have children. Tiana, a daughter of a count, is chosen to become mates with an elite knight, Adel, with whom she's always butted heads with since they were children. Arguing and bickering with each other, their completely unromantic first night begins. Tiana thought this would be their first and last night together, but Adel calls on her night after night, saying it's their duty... A romantic fantasy story of mates who can't seem to be honest with each other!