Translucent boormerang-shaped UFO seen over Kitakami

On January 10, 2012, an inhabitant of Kitakami (city located in Iwate Prefecture, in Japan) was walking his dog when he has spotted a large translucent boomerang-shaped UFO flying in the sky…

Witness report:

I was walking my dog near my home as I always do at the same time every evening.
The area is a park in front of my house.
It was snowing with no wind and it was a full moon so it was quite bright with the reflection
Of moonlight off the snow.
Snow was falling straight down to the ground. I was on why way back to my home when I heard a roaring sound coming from my left side(north side) I looked but could see nothing.
I heard it go over my head but could still see nothing until it passed to my right side. At that moment I saw a translucent boomerang shape with about a three meter wing span flying directly south towards a large fir tree. It was about two meters above my head and I only noticed it because of the trail of snow going over the objects sharp angled wings. I am certain the object was invisible apart from this.
I was in a state of shock. I took the dog home and went back because I was sure it must have hit the fir tree. But could find nothing.
I told my wife and a few friends about it but most mostly laughed at so I haven't really spoken to anybody about it since for fear of being ridiculed.
It's been a few years since the sighting and I can't remember the exact year and month.

Photo: 北上・みちのく芸能まつりの鬼剣舞 (Yoshi Canopus / Wikimedia) - CC 表示-継承 3.0