DBSK/TVXQ

I love this 5-boy acapella-dance fusion idol group, dong-bang-shin-gi. They are young-early 20s- pretty rather than manly handsome, and multi-talented in singing, dancing, composing, piano skills, etc.

What triggered my interest, however, is their agency and producer, SM. They seem to be extremely successful in entertainment business in korea, particularly in pop-music genre. The recipe of a successful show business idol...what is it?!