Okay, people. Time to clear this up.

Ryoga has been confirmed to show up (in the manga) in Japan (yes, that's the
Tokyo Tower), China (how else could he have gotten to Jusenkyo?), and in Vol.
38 of the manga, in ONE panel, Russia (the Kremlin is in the background).

The Kremlin also briefly appears in the anime, in the one week span Ryoga takes
before reaching Tokyo in the Breaking Point episode.

The 'Hawaii' some people thought Ryoga went to happens to be Okinawa. Of
course, how he crossed the ocean and collapsed on the beach in HUMAN form is
beyond me. Bad continuityu editing is what I think.

Any other place Ryoga is have to appeared 'in canon' (eg. America, Eastern
Europe, Australia) is actually a 'fanfic canon' thing, like the myth that only
women can use interdimensional mallets.

And in order to stop THAT potential thread in the bud, Ataru Moroboshi clearly
mallets Mendo repeatedly later in the UY series.

There. That's that.


=====

Kaze ga kawareba boku no michi sae sukoshi wa
Mashi ni naru daro
"Yutaka saga kimitachi wo Dame ni suru" nante
Shitta kocchanai

If the wind changes, even my path
Will probably become a little clearer
They say "Prosperity will make you bad"
I don't know about that 

- Empty the Pocket