Miyu is normal 8th grade girl, until her parents gets hired by NASA and they decides to dump Miyu to their family friend Saionji's place and take off to America. When Miyu gets to Saionji's place (She was told it's the big house on the hill), she realizes it's a old run-down buddiest temple. However Mr. Saionji decides to go on a 1 year long trip to India, leaving Miyu alone with his son Kanata (same age).
Things gets even more complicated when Alien baby and his babysitter pet crash-lands in their house. To make thing worse, baby starts calling Miyu and Kanata Mom and Dad, and starts floating around and showing ESP powers. Not to mention "capiable" Babysitter pet is not very "capiable".