Your dead!?!

Yai and his family are going on a family trip. Yai finds out that the the place is an abondoned apartment which is very peculiar. just when they reach the place, yai spots a boy on the 16th floor of the Apartment , looking at him. he's gets out of the car just to find him gone the next minute. yai gets curious about that boy and plans to find him this night. but will he find something else while living there?