100% OJ is only somewhat sweet. However, I think someone on OYP has said that Japanese OJ is supposedly sweetened to rather high levels. Otherwise, just chalk it up to the fact that, early on, someone decided that OJ is like a full-heal potion to yukkuris, and the rest of the fanon ran with the idea.
Ooh, ooh, according to the An-cyclopedia, OJ as a healing item was a reference to the game Dead Rising. (I just learned that the other day.)
I'd say orange juice in Japan tastes about the same as it does in the US. You've got your 100% juices, and then you've got your minimally-fruit-derived, sugar-sweetened Japanese equivalents to Sunny D. (They've also got tangerine juice, though, which is teh yum. Also, expensive.)
poweryoga said: Ah, interesting. But why orange juice from dead rising? :|...
If you played Dead Rising, you'd know how awesome orange juice was in that you got a good amount of HP back, especially when you needed it. either way, interesting. instaheal OJ for yukkuris came from Dead Rising....