Currency conversion

Remittance Services

• Transferwise
• GoRemit

See also Transfers on the Reddit r/JapanFinance community.

Stock Brokers

USD

• The budget brokers SBI and Rakuten charge 0.25 yen per dollar to convert currency: ¥250 for a $1000 conversion, ¥2500 for a $10,000, etc.
• Sumishin SBI Net bank has a cheaper rate of 0.06 yen per dollar, but you have to manually transfer the USD between the bank and the broker, which takes time.

When purchasing US stocks with Japanese yen, brokers add around a 5% buffer to the exchange rate to account for fluctuations in the exchange rate / stock price during the transaction. This is just an estimate - when the transaction is made the actual exchange rate will be used (subject to the 0.25yen/dollar fee).