when was the first ever prostate massage device made?

when was the first ever prostate massage device made?
it was when the first hand was created.
I am doing an investigation on the world first prostate massgae device that is used for medical purposes.
we have gone back to as far as 1996 but believe that it has been going on for longer than that with the following products
- enemagura
- onamagura


can anyone help me find the first ever product?

thanks

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