Japan Post Bank said it will stop customers from making new registrations or changing back accounts to use the e-money service by NTT Docomo for a while.
This is the uproar that is happening in Japan right now. The whole picture is not clear yet.
1. Obtain the victim's bank account and password by some means
2. The perpetrator creates an electronic money account in the name of the victim
3. Transfer by linking bank account and electronic money
According to media reports, it is speculated that this is the method.