I've finally got a pair of IJN flight goggles with a original case.
Goggles are around but not the cases, they are harder to find.
The goggles were made from Yamamoto Kogaku Co., Ltd (山本光学株式会社). For reference: Swans (eyewear) - Wikipedia, the free encyclopedia
What's more interesting is the case. I really like the the eagle art design.
the character from left to right:
航空 眼鏡(Kou-kuu Gan-kyou) - Aerial Goggles
Underneath the case wrote:
4 分隊 (Yon Buntai) - 4th Squad
小島 勉 - Kojima Tsutomu
The owner once removed the inner cushion materials in order to have a better or tighter feeling. So it was a custom modified piece.
I was very grateful to get such item !
Thank you for looking.