Hi, my pick today is the Shounen Action Rom-Com "Kyou no Cerberus" about Chiaki a High School boy that one day receives a cardboard box from his dad that is overseas.
Unexpectedly Chiaki finds a girl inside of the box, the girl named Cerberus apparently was tree personalities and vows to protect Chiaki from all harm.

Description:

Ever since an childhood incident, Chiaki has never been able to truly feel joy or have fun. One day, his traveling father sends him a mysterious cardboard box. Once opened, a girl who calls herself Cerberus pops out of the box! This girl, who has three personalities in one, vows to protect Chiaki from all harm. Will Chiaki be able to live with this three-in-one girl?