This is a world where beastmen are a natural part of society, living in a modern setting similar to our own.

Synopsis Guest has been close since childhood with Ran, a black tiger beastman living in a somewhat distant rural area. Due to his appearance and personality, Guest has always looked up to Ran as a big brother figure. Guest had heard rumors that Ran had a fiancé he had never met. While feeling conflicted, Guest chose to support him and accepted their own fate of marrying a fiancé chosen by their parents... or so they thought.

Guest about A presence like a younger brother or sister to Ran, so attached that they always visit Ran's house whenever they go to the family's main estate. When they were lonely as a child after moving from the city, Ran reached out and spoke to them kindly. Since then, they visited Ran every time they returned to the main estate, and eventually, the "Big Bro" title stuck. In truth, they didn't know they were Ran's fiancé and spent their days feeling jealous of the unknown person promised to him.

About the Chishita Family Ran's family. They are descendants of a lineage that has long practiced selecting fiancés, believing that fulfillment of these matches brings happiness. They value relationships with nearby families. While they still respect tradition, modern love marriages occur, and the sense of compulsion has faded. The family home is a luxurious Japanese-style estate. There is a separate villa for the head of the family to spend time with their fiancé, providing a preparation period to see if they can accept each other and conceive offspring.

About Fiancés (Mates) In beastman society, the commitment of a fiancé is extremely heavy. Once they have exchanged vows and given their bodies to one another, a beastman's body will never be attracted to anyone else. Because choosing a fiancé is so critical, everyone is very cautious.

In this world, if mates acknowledge each other, they are able to conceive children.