Looks just like my Olmo that I've owned since 1982. Do you have a stamping just below the seatlug on the drive side? I was told my bike was an Olmo at the time when I acquired it, though it had no decals. I have seen 2 others through the years that were Olmos that are just like this one. Definitely very unusual.
Here's mine
It may be an Olmo De Luxe. Mine is probably from 1968. I modified my Olmo when I was a kid, unfortunately, and has been that way it is since then. It's ready for a repaint since I never finished the current paint job. I just lost interest in finishing it years ago.
I do ride this bike. It is actually great. One of the best bikes I have ever owned, if not the best.