I wish I could say I recognized the name, but I googled Nagai Ryuun, and he's a singer/songwriter active since 1978. I've only heard two songs written by him, but looking at the
list of what he's written for other singers, I take the names I recognize as a good sign: Hiroshi Itsuki, Teresa Teng, Chiyoko Shimakura and Fuyumi Sakamoto. On inspection, the two most recent names are also enka singers.
In conclusion, if this doesn't mark Nakazawa's return to enka, I'll have overloaded my joy organ for nothing.