Here are some common reasons why transfers may fail:
Mistake in recepient's name.
Please take note of the characters used in the name of the recepient. Some of them look alike so it is easy to mistake the correct character for another.
Mistake in recepient's account number.
Japanese bank accounts should only have 7 numbers.
When looking for your bank account number, refer to your cashbook and look for the 7 digits under 口座番号.
In the event of JPPost Bank users, enter the first 7 numbers of the bank account number. E.g. Instead of entering 12345671, enter 1234567.