Is this the Optima Gamekeeper?
A few years back there were some done for Beeman, though manufacture had moved from Japan???? I think.

For some quirky reason the Optima Gamekeeper got a reputation over itself. Optically it was an excellent Hakko. When Hakko does it right they can be fantastic, like B&L can be compared to a Bushnell.

Anyhow, I can't see the picture. Not enough information to give more.

A mint Gamekeeper might demand £200 to a collector wanting one...badly.