I didn't set out to order these guys in any specific way, but looking at the list, there are basically three groups of players: young breakout candidates, veterans coming back from injury problems, and a couple of veteran ni-gun imports.
Sho Nakata (IF/OF, Nippon Ham): Nakata hit 30 home runs in 322 ni-gun at-bats last year, but every time I've seen him at the ichi-gun level he's looked overmatched. Supposedly he's a butcher at first base, but this spring Ham is giving him a look in left field. If he can stick with the big team he should get enough at-bats to get comfortable.
Romash Tasuku Dass (P, Nippon Ham): I'll admit that only real reason Dass has caught my eye is that he's half Indian. I didn't really follow him at all last year, but apparently he only saw 15 innings of work at ni-gun.
Kohei Hasebe (P, Rakuten): Hasebe was heavily hyped as an amateur but has so far had two lackluster seasons as a pro. Rakuten has a deep rotation, and we'll see if he can flourish under Marty Brown.
Yoshinori Sato (P, Yakult): Yoshinori has a great arm, but is basically a two-pitch pitcher with command problems. If his command improves I think he'd be as good or better than Wirfin Obispo, who has a similar arsenal.
Shota Ohba (P, SoftBank): Ohba has shown that he can get NPB hitters out, but has yet to put together a complete season. The talent is there, though.
Yasuhiro Ichiba (P, Yakult): Ichiba was another highly regarded amateur who has failed to make an impact as a pro. I thought a change of scenery would help Ichiba last year, but it didn't. This year, he's experimenting with a new, three-quarters delivery.
Makoto Imaoka (IF, Lotte): From 2002-05, Imaoka was one of the most competent, productive hitters in Japan. From 2006-09, he got progressively more horrific until Hanshin finally released him. The Marines are giving him a chance to contribute this year, and hopefully he'll play like he has something to prove.
Yoshinobu Takahashi (OF/IF, Yomiuri): Takahashi is a guy that Hanshin fans love to hate, but I've always thought he was a very good player, perhaps even a little underrated. In my eyes, he should have been the Central League MVP in 2007, instead of Michihiro Ogasawara. He's been battered an ineffective over the last two years, and even if he's healthy this year he'll have to compete for playing time.
Nagisa Arakaki (P, SoftBank): Seven years ago, I thought Arakaki was Japan's next great pitcher. And he was pretty good for a while, before catching Steve Blass Disease and dealing with shoulder injuries (two problems which are probably not mutually exclusive). Arakaki has been indefinitely relegated to ni-gun, which suggests he has a long way back.
Aarom Baldiris (IF, Orix) & Juan Muniz (IF, Lotte): Baldiris and Muniz have a few things in common - they are both veteran minor leaguers, both started in Japan on ikusei contracts, and both led their respective farm leagues in batting last year. Baldiris is younger and has gotten time at the top level, where he hasn't hit enough to stick despite strong defense. We'll see if either break through this year.