I'd also go for a Jolt Pearl or Solid. The coverstock is smooth but offers good traction, and the core gets the ball into a roll and finish, this will help you. The Rampage is overall a stronger option - versatile, but IMHO too much for a beginner. Cannot say anything about the Pluto, though, never seen one in action around here.
Differentiating between balls is mostly by the coverstock. High end pieces tend to have very aggressive coverstocks, coupled with powerful cores. While they offer a huge hook potential, they make IMO only sense if you have a developed stable game, where you can exploit the ball's potential through setup, drilling and proper use. Remember: the hook in itself is not the goal of the game, but carry - and in most cases a less modern piece (mid range) does the same job, just not as spectacular, seen on TV and with a bigger price tag. Many mid-priced balls use coverstocks from former ball generations, and their cores tend to be milder - even though some special purpose pieces can be very powerful, too.
IMHO, they offer anyting the "normal" bowler might ask for - Ebonite's Bash & Clash are a very good couple of balls that would, plus a spare, cover more than 90% a typical bowler might encounter. Brunswick's Rampage and Wizard are pretty much the same, as well as Hammer's Doom and Anger, just to name a few. The variety of options is confusing!
Entry level balls are commonly the mildest pieces in a company's assortment - but they are in no way weak! The Tropical Storms or the Power Grooves are pretty strong pieces, and very good value for the money. The High Flare Scouts are also stronger than would think in the first place. They normally have simple cores (pancakes or weight pucks), that distribute weight to the cover and get the ball well down the lane, for a controllable hook that is easy to control for a beginner.
The Rampage is already a mid-range piece, while the Jolts fit between entry level and mid-range.
If in doubt, talk with the local pro shop, and maybe try to bargain (although difficult in Japan...) about a complete package with shoes and a bag - two additional useful equipment parts, and mayn shops offer such packages at better rates than bought seperately.
--------------------
DizzyFugu - Reporting from Germany
Confused by bowling?
Check out BR.com's vault of wisdom: the unofficial FAQ section
Secrets revealed: What's a fugu?