Gordon,
It belonged to my Japanese wife's grandfather who passed away at 101 last year. He was a Shinto priest in Gifu. I have no reason to doubt that it's real. With looking at it up close, it looks real to me.
With the similarities of the piece I found online that is Nagoyamono, and being that Gifu is close to Nagoya, it makes sense to me that it would be Nagoyamono.
I would love to hear from anyone that might be able to provide more details on Nagoyamono...