The switching method is as follows:

1. In the store, click three, as follows.

2. Next, you need to click on the account, as follows.

3. Next, you need to click on Account Preferences, as shown below.

4. Click to add a credit card or debit card, as shown below.

5. Click Continue to switch your country region to Japan.

6. The effect after switching is as follows. The stores are all in Japan. Note that you can only switch once in a year, according to the official statement.