Two-step data flat Z(Mobile phone)

A Flat-rate Data service starting at a fixed monthly rate of ¥0 available for 4G LTE (au VoLTE supported) mobile phone users.


  • Flat rate gives you peace of mind when using emails and the Internet.
Monthly flat rate Data communications charges for
the data that exceeds 500KB.
Monthly maximum charge
¥0~[1] ¥0.03/KB ¥4,200
  • [1]The flat rate includes free communication allowance that is equivalent to 500KB.
  • * This Flat-rate Data service cannot be applied to data communication charges incurred from overseas use.
Rates image
  • * The Internet may be accessed in some applications even when a user does not operate the device, possibly exceeding the amount of free communication allowance(500KB).
  • * If you change a 4G LTE model to another 4G LTE model and the change of a rate plan/Flat-rate Data service is applied from the date of the change, data communications charges on the date of the model change are calculated with the new Flat-rate Data service. For this reason, the amount of data you use may exceed the amount of free communication allowance due to the amount of data you used before the model change, possibly reaching the upper limit.
Application Required
Flat rate Required

Eligible models

  • 4G LTE Feature Phone (au VoLTE)
  • mamorino Watch

* This service is not supported on AQUOS K SHF31.

Applicable period

If you apply when subscribing to a new contract or when changing your model, calculation on a prorated basis is applied from the date of the subscription or the change (including free call allowance). Changes in the contract or switching to the model you bring to a shop take effect from the following month. If you cancel in the middle of a month, calculation on a prorated basis is not applied and the flat rate is incurred.


  • * au Smart Value and au Smart Value mine are not available.
  • * Data Charge, Data Gift, Data Carryover, Long Term Hospitality Data Gift, au STAR Loyal, and au Wi-Fi SPOT are not available. Extra Option is available.
  • * Data communication charges incurred from overseas use are not covered by this Flat-rate Data service. Two-step data flat for Overseas is only applied when your device is automatically connected to an eligible carrier.

Two-step data flat for Overseas

Restrictions of communication speed

  • If the total amount of communications exceeds 2GB in a month, the maximum communication speed for sending and receiving until the end of that month will be 128 kbps. (The communication speed restriction will be removed on the first day of the following month.) If you apply for the Extra Option, the communication speed restriction does not apply.
  • To avoid network congestion, a limit may be placed on the communication speed for a whole day if the total amount of communication used exceeds 6GB over the three most recent days (not including the day on which the restriction is applied). The restricted speed will differ depending on data traffic conditions. (The restriction applies regardless of the remaining data amount.)
  • Regardless of whether you are subscribed to a Flat-rate Data service, your line may be temporarily suspended if the cost of the packet communications you use becomes high.

Communication amount notification

  • Customers are notified via SMS (C mail) when the remaining amount of their monthly data amount drops below 10% or reaches 0% during the current month.
  • * The actual amount charged is calculated using the tax amount calculated from the total amount of the individual tax-excluded charges, and therefore may differ from the total of the individual tax-included charges.
  • By phoneOpen 9:00 – 20:00

    • English

      0120-959-472(Toll Free)

    • Portuguese

      0120-959-473(Toll Free)

    • Chinese

      0120-959-476(Toll Free)

    • Korean

      0120-959-478(Toll Free)

    • Tagalog

      0120-933-952(Toll Free)

    • Vietnamese

      0120-933-961(Toll Free)

    • Japanese
      about au mobile services

      157(Toll Free)from au phones

      0077-7-111(Toll Free)

      about Internet services
      Contract / Fee / Billing

      0077-7084(Toll Free)

      Connection setting / failure

      0077-777(Toll Free)