There can be several reasons for that.

Please check the following to see if any of the following cases apply to you before contacting us:

1. Calling Rates

As a reminder, under our Voice+Data plans, calling and texting (SMS) rates are charged separately from your regular basic monthly fee.

※Your monthly fee covers your data cost ONLY.

Our rates can be found here: Call & SMS rates

If you use Sakura Mobile’s prefix number (0077-502-010), your rates will be discounted. Otherwise, you will be charged at the normal rates.

2. The monthly fee is much higher than last month

If you started your contract with us recently, please check your contract start date as your first month's basic fee is prorated. From the next month's usage, you will be charged the full basic monthly fee.

Prorate means that you will only pay for the ratio of the days that you have used for that particular month. 
Both monthly fees and data will be prorated for the first month. 

※ The first month's bill of your contract is prorated, which means that you will only pay the amount starting from the start date of your contract, to the end of the first month.

※ As you are only paying for the days that you use the product for the first month, the data is also prorated. This means that the allocated data for the first month will also be the amount from the start date of your contract to the end of the first month.

Also, please check our billing cycle; The service fee for a month will be invoiced and paid at the end of the following month.
(e.g. Fee for March will be invoiced and charged at the end of April)

FAQ: When is the monthly fee charged?

3. Other reasons

If the above (1. and 2.) does not apply to you, please contact us via contact@sakuramobile.jp by email.