My dad has have this bass for years before i was born
He bought it as second had
It looks so much like a gibson eb-3
he repaint it like 3 times and cant remember if it said gibson somewhere before...
Inthe back plate it says its made in japan and has the number 91(like if it was the serial num)
That's cool, post a pic for us to see. There were a LOT, I mean a LOT LOT of copies of the EB-3 made in Japan back in the 70s and 80s, by multiple factories, putting dozens of different "brand names" on the headstock. It was a popular thing at the time.