[lottin]

It hasn't lost half its value. A "weak yen" simply means the yen depreciated relative to another currency.

[RichEO]

Yes but there’s inflation too. The yen has devalued, but also the cost of goods in USD has gone up.

[lottin]

Japan has low inflation, like most developed countries.

https://fred.stlouisfed.org/series/FPCPITOTLZGJPN