There's quite many famous JP VA's in P4 (though not as star studded as P5's). Daisuke Namikawa plays Yu Narukami (Hisoka from Hunter x Hunter), Rie Kugimiya plays Rise (Kagura from Gintama) and Ishizuka Unshou plays Dojima (Professor Oak and Old Joseph Joestar).
Oddly enough, Vic Mignogna, who is Ed’s english VA, sang two of the One Piece openings for the Funimation dub. The dude is a great VA.