This isekai fantasy story centers on a man who dies due to overwork, a phenomenon that has unfortunately become a known problem in Japan. Just before dying, the man thought that if he was reincarnated, he would want to live the lazy life of a rich man's dog. His wish is granted, but it doesn't turn out the way he anticipated. He comes back to life in another world as Rōta, a dog who belongs to the kind-hearted Mary, the daughter of an extremely wealthy family. However, at just one-month-old, he is easily larger than a human, and he realizes he is no ordinary dog!