After mentioning the new Sephia 2500S and 2500SDH models earlier today, I got a kind advice at the TackleTour Forum, to examine the brand-new and promising Ultegra Advance model, that was officially announced just two days ago at shimano.co.jp and that seems to be exclusively merchandised in Japan.
Further research at google ended up with just three results - one of them linked with the shop at Plat.co.jp where the reel is already listed in the “coming soon” section. At least the rough google translation gives information about technical specifications and specific features.

Gear Ratio: 5.0
Weight: 265g (~9oz)
Line Retrieve Per Crank: 70,7cm
Line Capacity (lb-Meter): 3-160, 4-130, 5-100 and 6-75
Max Drag: 9lb (ca. 4kg)
S A-RB Ball Bearings: 5
Roller Bearings: 1
Posted: November 5th, 2008 at 10:56 am
I have the one year older(’07) Gold bodied 2500 Ultegra and they too have a short spool option. From what i have found out myself they have an optional buy it yourself shallow spool. Since Japan doesn’t give out a spare spool like the US does. I’m currently looking where to purchase a short spool for my 2500. I’m located in CA