My lovely half-human, half-beast

The female protagonist saw a puppy in a box on the street. It was Jimin, a half-human, half-animal dog. Jimin had been abused by his previous owner, so he trembled when he saw people. The trauma was severe. Jimin was crying in the box. The female protagonist took the box home. When the female protagonist went to take a shower because it was hot, Jimin transformed into a human. Jimin was only eight years old. When the female protagonist came out of the shower, Jimin was shaking from the trauma.