Please I want to know where can I buy the Megahouse 2x2x4 and the 3x3x3 assemble puzzle. My dad's now in Tokyo and he'll come back this Saturday. I showed him the pictures of those cubes, but he can't find them anywhere. Please does anyone know where to buy those cubes near Tokyo? Thanks.

I bought 2 at Bic Camera in Shinjuku a few weeks ago even though they were out of stock on Bic Camera's web sales site. Bic Camera has branches in several locations in Tokyo and elsewhere in Japan, so other branches might have it too. The price was 1,320 yen. If your father spends 10,000 yen or more at one time and his status in Japan is Tourist then Bic Camera will do a procedure to refund the 5% consumption tax (or at least they used to).
I don't recall seeing that for sale in Japan. Wasn't Meffert the original source for that one? Wouldn't you want to buy that one now either from him (if still available) or from certain other unmentionable sites?

There are also full price stores such as Torito and full price chains such as Tokyu Hands.

Where is your father staying?