Japan has perhaps the cleanest currency in the world. Finding a ripped/worn-out note is pretty rare.

They have had problems with the currency though. The ¥2,000 note was issued but retailers were reluctant to use it. A bit like the $2 in the USA, only a lot more valuable.

There was also the issue with ¥500 coins. The Korean 500 won coins (worth 10% of the yen) were being used by scammers in Japanese vending machines, so Japan came out with a new ¥500, only it wouldn't (and still doesn't) work in many machines.