How good is the network coverage of this SIM card?
You will be on the top telco in Japan (Softbank) and South Korea (SK Telecom)
What does infinite data mean?
Infinite data means there is no data limit nor speed cap on your usage. You can hotspot it and use it as much as you can and the line will not be cut off.
Can this card be topped up?
No you cannot top up this card. After 8 days you will not be be able to use it. Remember the 8 days starts based on Hong Kong/Malaysia timezone.
Can I use Whatsapp to chat and make calls with this card?
You certainly can. Using Whatsapp to call saves you money.
My phone is region locked and can only accept South East Asia SIM cards. Can I still use this card?
The new Samsung phone models have a sticker showing “South East Asia SIM Cards only” in the packaging. The message simply means you need to use a South East Asia SIM card to activate the phone. After you made calls of at least 15 minutes with the phone, your phone will then be able to use any SIM cards worldwide.