Kanai Yano, a 28-year-old single woman with no boyfriend, is suddenly summoned to another world. There, she encounters Rita Scryne, the duke's daughter who looks exactly like her, and Rita's father, Zack. They ask her to take Rita's place in an arranged marriage with the ruthless and feared King Eugene Astaroth—known as the "Merciless Wolf." Upon learning that the summoning magic can bring people from another world but cannot send them back, Kanai finds herself with no choice but to accept. However, when she meets King Eugene, she makes a shocking discovery—his true identity is none other than...! Thus begins a fantasy romance where fate reunites two lovers in an unexpected world.