Please log in to "Web Billing" and register "Seikyu gaku Oshirase email (billing amount notification email)" service.　

Then the service will be available. In the case of "Omatome Seikyu Service (combined billing method)," you can register only the main line to receive "Seikyu gaku Oshirase email" service.

You can't register a sub-line to receive "Seikyu gaku Oshirase email" service.