I have similar concerns. My first trip to Japan is in 9 days. I'll be staying at:
The Westin Tokyo
1-4-1 Mita, Meguro-ku,
Tokyo 153-8580 Japan
My HP Laptop has a US type 3 pin plug (the flat plug blades are not polarized). Should I get an adapter? Or an HP power supply for Japan's different electric Voltage & Hz?