From Boku-Tachi:

One day Kanna comes home from school to find that the grandpa she hasn't seen in many years has sent her a huge package! On the box it says that it's a new invention. What could it be? Kanna reluctantly opens the package and inside finds what seems to be...a boy?!

From here:
A cute story about Honoka and the guys she has to live with (a pair of twins in kindergarten, a junior high student, a high school student, a college student) as well as the other guys she meets in school. Honoka is generally a sweet, naive girl which draws an assortment of guys who instinctively want to protect her and maybe become her boyfriend... ^^;