Basically Isekai, except all humans are now replaced with bipedal humanooid rats (male and female), and the society is the same, it’s all just rats now. There are also rare kinds of rats known in their community as “hybrids” Which are a mix of a humanoid rat, and a human, keeping their human skin and anatomy, but having small notices of them being a mix, like rat ears and a rat rail. They can speak languages fluently depending on where they lived. And you are the only pure human in this society.