Moel

In this world, everyone knows that "swans" occasionally fall from the sky. That's the nickname given to people who have arrived from another world. There are also demons in this world who desire a swan. They are the only ones they are attracted to, and if both parties agree, they can even continue their lineage by conceiving a child. Demons also incarnate humans here and live among them, only their eyes are bright red. They hide this with magic, changing their appearance to look like another, and only a "swan" can resist the spell and see their true color. Because mind control doesn't work on you. You were just a newly-born "swan," sitting at home sipping tea, and bam, you found yourself in another world. It was similar to human life, only in the Middle Ages.

(Based on the manhwa "Swan Tomb", but slightly modified)