You're My Pet (2011)

On a rainy night, Eun-Yi walks home and finds a large blue box on front of her home. When she looks inside of the box she's shocked again to see the named In-Ho, sitting in the box. Ji-Eun brings sopping wet In-Ho into her apartment, while she tries to contact her younger brother. Her younger brother doesn't answer her calls. Oddly enough, In-Ho reminds Eun-Yi of her former pet dog Momo. Eun-Yi then comes up with an arrangement. She will let In-Ho stay at her apartment if he will become her pet dog named Momo.