Cool! I worked on quite a few of that series! I had a friend who worked as a salesman for the Yamaha distributor in the Netherlands and he often brought them in for simple set-up jobs.A Japanese auction impulse buy of sorts.
This was bought in a Japan based auction site I go to when I’m looking for something particularly odd that wasn’t offered in the US. I found what appeared to be a catalog from the era with this series of guitars and oddly enough the SG-65 was omitted entirely which leads me to believe perhaps it was for domestic Japanese market only. I been collecting old Yamaha stuff for years and the only Yamaha electric I ran into from this era was a Jazzmaster inspired SG-3 but other than that anything before the late 70’s more often than not was an acoustic or classical which is weird that Yamaha didn’t seem to import electrics into the states until the mid to late 70’s but seemed to have already had a considerable foothold in the American market in the flat top acoustic market. So much so that a Yamaha FG-150 was played at Woodstock by Country Joe Macdonald.