I have one entity - User. It is described by User.class.
Hibernate creates one table per entity, so when I call session.save(user)
Although i have never used but there is a concept of Secondary Table in hibernate. And @SecondaryTables is the annotation in hibernate by which an entity can map more than one table to fetch the data. The entity which is fetching data should have @SecondaryTables annotations. It associates secondary table on the basis of primary and foreign key and also on the basis of unique constrains.
Here is one sample I found after doing google, check whether it helps you to achieve :
http://www.concretepage.com/hibernate/secondarytables_hibernate_annotation.php