CHIBA, Japan — The next big star is coming. Everybody knows it. They will not say so because he will not say so. He will not say so because Japanese baseball stars are not supposed to leave home early, and he has already broken a few rules.

But Roki Sasaki, a 6-foot-4 right-hander with a tantalizing arsenal, is coming to Major League Baseball as soon as he can. And because he is so eager and because MLB teams are so eager for what he can offer, Sasaki seems almost certain to eschew tradition by pushing to leave for the United States sooner than almost any other Nippon Professional Baseball player has.