Kimi wa Petto (2003)

Smart, successful and good-looking Iwaya Sumire works for a big newspaper. However, her boss asks her to leave for being too "perfect" a woman. Feeling angry and dejected Iwaya returns home depressed, and most of all lonely. However, when she finds an unconscious young man lying in a box out the front of her home and takes him in. He looks like a dog she used to own called Momo. She dubs him Momo and decides to "keep him as a pet." It's the start of an unexpected life together as they overcome obstacles and become quite attached to one another. But can love like this exist? ~ TBS