If it is selling into Japan, as Yen drops in value your customers will find your prices too high, so sales will drop, or you will drop your prices to maintain sales. Either way , you make less money when expressed in Yen. But the reduced earnings in yen becomes much reduced amount in USD.
Now value of stock in inventory will initially rise in value in terms of yen, until you adjust your prices downward to sell.

Values of other assets will rise in terms of yen but decline in terms of USD as imported inflation sweeps Japan.

If you are buying Japanese products for sale in the USA, Japanese products will become less costly to Americans, so your margin can rise, your profits rise.