Nikukyun Ongaeshi ~Tasuketa 2hiki ga Onna no Ko ni Natte Yattekita~

The main hero is resting alone at summer vacation. One day he walks along the river and found a kitten and a puppy which someone threw out in a box on the street. Since he had a kind heart, he decided to give them shelter and take care of them. Everything went well, but once both pets disappeared. A few days later a hero arrives home and to his surprise he finds there two beautiful girls.
Unknown magic turned a kitten and a puppy into people because of their desire to thank the kind person. But what the hero didn't know was that their the gratitude become dissolute…