Sharapova's not going because she's already played Birmingham. Top players aren't allowed to participate in more than one Tier III event.
I think Nicole will turn up to defend her title. And on the tournament's website, both Kirilenko and Safarova have made an early commitment. Others likely to turn up are Golovin, Jankovic and all the other top Japanese players, save Sugiyama.
I'm not holding my breath for a bunch of big names to turn up though. They usually withdraw about one to two weeks before the tournament starts. Sometimes I don't know why they even bother to nominate themselves to play in Tokyo