I am an analyst of Dalian Huiju, the general agent of NBG foreign exchange platform in the northeast of Britain. I hope this will help you understand this;

You can go directly to a large postal savings bank (above a branch) to purchase foreign exchange and remit it to a friend's account in Japan. He will withdraw Japanese yen when he withdraws money. The handling fee for your remittance is very low. When RMB is converted into Japanese yen, it is converted at the current exchange rate, and the specific real-time exchange rate can only be known at the time of conversion. If you remit money in Japanese yen, the handling fee will be much more expensive than the remittance fee. It is not recommended that you remit money in this way. In my experience of remittance abroad, the postal remittance fee is the lowest, and the most expensive is the foreign bank.