Should I buy this 3G travel card ?

can someone help me check this out to see if it is a good product.I just want a card to use google map and twitter.
linky: http://us.hoyoyo.com/?s=onlineCard

I wouldn't recommend it unless you have a very specific use case where you only want to use internet 10 times within a 180 day period. Otherwise there are potentially cheaper and faster options such as rental wifi hotspots and sim cards widely available.

How long will you be travelling in Japan?

During my stay in Japan I used Econnect 3G Sim card, it's for 30 days, quite cheap and they send it to your hotel. It helped me a lot to check train schedules and other stuff.

http://www.econnectjapan.com/

Econnect is a viable option. Also check out b-mobile, pupuru, and global advanced communication.

In my opinion 3G speed is not enough sometimes. I have not tried such staffs and I always renting a LTE WiFi device from pupuru. If you will travel in small group WiFi might be better since you can share the connection.

I would agree, and would also recommend an LTE pocket wifi for the speed increase over 3g.

The thing is I will probably go to southeastern Asia for weeks. And this card is rechargeable, so maybe I will still have a try, wish me luck.
Thank you guys!

I forgot to mention that each time you use it you are capped at 100mb.

If you only need it for Japan, I'd recommend looking into something like the econnect sim instead. It's also rechargeable if necessary, and a better deal if you go for the unlimited card.