My gramma previously had a contract with SoftBank for the 108SH.

The charger works fine, and I can turn it on, but since I removed the SIM card, the message 'Please insert the USIM card' appears, and I can't proceed further.

(It's a phone that can't be operated without a SIM card.)

I removed the SIM card because when I operated it with the SIM card inserted, contract details such as phone numbers were retained.

Please be aware that after turning on the power, you can't proceed further. Please consider this before making a decision.