Section 16 of the National Tax Agency's "Tax treatment for crypto assets (FAQ) - Japanese only", published in June 2021, clearly states that when you give coins away for free, you need to report it as a SELL.
EXAMPLE: You gave 0.1 BTC to a friend for free. The market price of 1 BTC at the time was 5,000,000 JPY. This activity should be represented in the custom file as follows:
|Date/time when you gave the position away||SELL||Anything||BTC||0.1||
(*1) If you leave this blank, Cryptact will lookup the market price in the settlement currency.
To download a sample custom file, please refer to this article.
* The NTA's FAQ states that "the gross income amount can be set to an amount equivalent to 70% of the market value". Please set the price field at your own discretion accordingly. Please consult your local tax office if you wish to set the price field to something other than the above or the market price.
* Note for the recipient side. If the gift is from an individual, please upload it as a BUY trade at the market price and note that it may be subject to the gift tax. If the gift is not from an individual, please upload it as a BONUS.