Dave, you are right. Thank you very much for giving me the right direction.
Concerning material: It is not cast, but made of brass sheets.
Concerning quality, thanks to the Toppei hint I was amazed to find similar worked sheet metal with hozon certificate.
I am looking for information concerning this koshirae. I was told it might be from the russian-Japanese war. Obviously it is not made for battle. The tsuba looks odd and the brass seems to be machined. The negoro stylish saya might be a reference to the koto inside. Who wore such mountings and at which occasion? Is there recommendable literature?
Looking forward to your expertise with kind regards,
Robert