Can I use the Bestek Travel Converter power strip in Japan?

http://www.bestekcorp.com/product/power-strip-travel-converter/4-usb-port-with-uk-us-au-eu-plug.html

Ok, I live in Japan. My friend from US came to visit and brought this product and then left it when he left. I know that Japan and US have similar voltage (100v and 110v), and typically a converter is not needed. However, I want to use this just as a charging station for my portable devices (a US laptop, JP iPhone, JP 3DS, etc). Can I use this just as a normal power strip?

Secondly, this power strip comes with an EU plug and 3 plug adapters. My friend forgot to give me the plug adapters, so I'm stuck with an EU plug I can't use. Can I buy a generic EU to US/JP plug adapter and use it with this?

GO TO YOUR STORE IN JAPAN TO BUY A PLUG ADAPTOR, OR CUT AWAY THE USA PLUG AND THEN REPLACE IT WITH JAPAN STANDARD POWER PLUG.
USA USES 120Vac RATHER THAN OLD DAY 110Vac NOW. JAPAN 110Vac IS A BIT LOW FOR 120Vac DEVICE BUT TRY IT!