Step 1: Export the private key or keystore file of the address from PIwallet
Option 1: Export the private key
Option 2: Export the keystore file, which also means json file in MetaMask.
Step2: Open MetaMask, click import account.
Option 1: Import with its private key
Option 2: Import with the json file (keystore file)
Then you will see the address in your account list.
Step3: Connect to Plian network, you will see the PI token in the assets list.