Well, I am having a very hard time finding One Yen and Five Yen coins in UNC/BU (without problems) with the dates Showa 35, 36, 37 (1960, 61, 62). Plenty of chewed up/severely-worn examples to be found, easily. And 1969 (Showa 44) One yen is hard to find in decent condition, too. There are plenty of them on eBay, but they are all in that expensive 1969 Bank of Japan mint set.
These seven coins (in UNC+ grades) almost never come up for bid anywhere. They are listed in catalogs at low(er) prices, too; even in high grade.
I have a "Toho Planning" coin binder (album) from around 1980. I have these early 60s dates in the holes, but they are all very rough for wear.