Please follow the steps below.
(1) Tap "convenience store top up" on the home screen of the app.
(2) Specify the top up amount and get a receipt number
(3) Pay in cash at the convenience store of your choice. For details, please refer to the followings:
How to make payment at FamilyMart
How to make payment at Lawson and Ministop
How to make payment method at Seicomart
For the top up fee, please refer to the following:
What is convenience store top up fee?