Question about remittance, conversion to JPY and tax implications

Hello everyone 👋🏻,

I've got a question regarding remitting money to the Japan, converting part of it into JPY and what it means for my tax return next year. Here's my current situation:

– moved to work in Japan on February 2025 – I did not work and did not have any foreign source income in January 2025
– as far as I understand it, in the eyes of the National Tax Agency, I'm considered as a Non-Permanent Resident
– in March 2025, I transferred 100,000 USD from my checking account in the US to my Sony Bank USD savings account here in Japan (note that no conversion happened – the money stayed in USD the entire time)
– in April 2025, I converted 10,000 USD to JPY within Sony Bank (so the money ended up in my yen savings account basically)

One thing I want to stress is that the 100,000 USD was money in my checking account in the US and not money gained from foreign income source nor stocks, dividends, etc… (I mean it was but in the years prior 😅).

Now here's the questions I've got for the community:

1. Does transferring the money from the US -> Japan require me to file a tax return and/or pay taxes on it?
2. Does converting part of the dollars to yens require me to file a tax return and/or pay taxes on it? If so, how should I calculate the exchange rate gain?

Thanks a lot for your help!

EDIT: Updated the message to clarify that I did not have any foreign source income in 2025