I was thinking the same as
bondingo. They are beautful ballads (the one you have listed that i have heard), but i would have never considered these enka.
Yoko Nagayama's Jonkara Onna Bushi is true enka (to me):
http://youtube.com/watch?v=jfNHljz2Ka8
The only Enka songs with a pop twist I can think of are Yuko Nakazawa's old releases and Yuki Maeda's. Fujimoto Miki also released a beautiful ballad recently, but i am not sure if it classifies as enka..
http://youtube.com/watch?v=4tkgaZ22E8A (nakazawa)
http://youtube.com/watch?v=K094zgcN8xU (maeda)
http://youtube.com/watch?v=dQ6AwcJPBM4 (fujimoto)