How to use it :
1. plugs it in the wall outlet.
2. plugs USB cable in this adapter, then power charge starts.
I thought it would cost about 500 yen, so I gave 500 yen to my daughter. My daughter went to an electric store (Yamada denki) with 500 yen, but she found it cost more than 800 yen. She chose a cute one of 1280 yen ($13.20 €10.00). Actually it is Hello Kitty version. I gave additional 780 yen to her later.
Today's room temperature is 31.7 C.