They don't have the 4GB GTX 970 option here. It is either a 2GB GTX 960 (included in the price) or a 6GB GTX 980Ti (for another $700.00 (ouch!). Before the Skylake models came out the default was a 2GB GTX 960 or an optional a 4GB GTX980 for another $400). (1USD = 120 Yen)
well it sucks a bit, in Canada, HP offer no customization for that PC and in the US, you can change about everything.