One of the best option is probably to get a B-Mobile SIM cards, which are the perfect SIM or micro-SIM cards for those who are happy with data-only service for their smartphones or tablets while travelling in Japan.
Don’t forget that in order to use these SIMs, you must have an unlocked device and be able to configure the device to use the SIM. The B-Mobile SIMs are data-only SIMs, but you can use them to make Skype calls (or calls using other similar services), so you can use your device like a phone if you wish.
While there is a direct exit from the platforms that will take you to BIC Camera, it’s easier to find by going out the normal main exit on the north side of the station (known properly as the Karasuma Central Gate). This is the side from which you can see Kyoto Tower (if you can’t see it, you’re at the wrong exit).
Exit Kyoto Station via the Karasuma Central Gate and take a left as soon as you’re outside the building. Follow the sidewalk around the front of the building (it will jog left then right) and walk past the entrance to a parking garage and after a minute or so, you’ll find yourself in front of BIC Camera.
Take the escalators to the 4th floor and go right to the cashiers. Ask them in simple and plain English for the B Mobile SIM. You might have to write down what you want if the person behind the cash register doesn’t speak much English. They’ll take out all the various B Mobile visitor SIMs and microSIMs. Note that these SIMs require a call from a Japanese cellphone call to activate them. Usually the staff are happy to make that call for you with a store phone to activate the SIM.
Once the card is activated, you’re good to go.