First off, if the Sailor Moon characters existed in the Marvel universe, they'd also have Sunfire as a national hero before Sailor Moon came along. Not to mention all the misadventures Wolverine has had in Japan.
I was thinking more Toei’s Spider-man then the entire main Marvel Universe
Though this reminds me of a really bad idea for a fanfic I had in high school where Minako knew of Gwen Stacy when they were in London and was going to travel to New York to kill the Green Goblin after finding out about Gwen’s death (I said it was a bad fanfic idea) and it was going to crossover with Spider-man (the mainstream version)
Hey, if we're going to talk a crossover of everything else Toei has done, maybe we should include the 1989 X-Men pilot done by them?