Why are you under the impression the user atanaka exists and even if user exists why they would have rights to log in with workbench or adminui. Have you tried logging into adminui with administrator/password?
Is there any user who is able to login to workbench. If yes, please match its role and permission with user "atanaka".
Minimum rights(role) to login in to the workbench are:
1. Application Administrator
2. Services User
If you have any further, revert on this thread.