Data SIM for a Pocket Wi-fi Device?

In previous Japan trips I have rented an all inclusive pocket Wi-fi device from Advance Global Communications (I think) that had unlimited data. I now actually own my own pocket Wi-fi device (TP Link thing) and was wondering if it is possible to get an unlimited data SIM to use in Japan with your own device as opposed to a rented one? I am hoping it would be a bit cheaper!

If not unlimited what sort of deals are you looking at? I do use a reasonable amount of data, streaming video on trains and in hostels it an eve as I usually travel alone. Would it just be cheaper to rent the full package and leave my own at home?

The ones I see are pretty expensive for small amounts of data, not unlimited. For an unlimited data sim you might need to get something on contract, and might not be that much cheaper overall. The GAC and other providers like JapanWireless are around 300 yen/day (after the initial fee) which isn't so bad.

Many wifi devices offer for tourist in Japan are usually unlimited data, as for SIM card, this is also the same, but there are limitations, and the restrictions are usually the first few GB (depending what you buy), have full speed, anything after that is limited to about 128kbps, for your use its not possible are this speed is probably only good for messaging, slow browsing etc., streaming is not possible at this low speed.