I had not heard of this Yashima camera, but found the following...
(if you look for value, check eBay sold listings or post an ad in RFF Classifieds)
Yashima Kogaku was a short-lived optical company set up as a division of a Yashima company that was an OEM for audio components. It was run by Ushiyama Jisaburo, a brother of Ushiyama Yoshimasa, the founder of the much earlier Yashima renamed itself after its Yashica products in 1958.
Yashima produced one 35mm SLR, the Yashima EMC750 released in August 1976 (also sold as the Osanon Digital 750 and Rony EMC750). This was an aperture-priority AE body with an M42 lens mount.
Yashima went bankrupt in the early 1980s.