Why is the PSP lowering in the US and Others and rising in Japan?

[bbsin]

Everyone in Japan already has a DS and PS2.
No one in Japan cares for Xbox360.
The Wii is supply constraint (i think)
And the PS3 is too expensive (especially considering the economy), and does not yet have the library that the Japanese audience wants.

So that really only leaves the slim massively multi colored PSP.