Ultra is like a Hallertauer Mittelfrüh combined with Saaz. Spicy AND noble characteristics.
Sorachi is just a girlie hop compared to it.
Most Japanese traditional lagers follow the Budvar way of Saaz hops.
But you DID say rice lager, not Japanese rice lager.
IMO any lager that's lightened with rice needs a spicy traditional, noble type hop -yen and yang.
Since Ultra is considered a aroma hop, I would go with what Miraculix said, Magnum applied for bittering -first wort it to tame it, then I'd apply Ultra at 10 minutes before flame out as that time slot is where you get most pizaaz for flavoring along with aroma -IMO of course.
I push Ultra because I don't want to see it go away, to keep in demand means hop growers will cultivate it. And I did a single hop Dortmunder with only Ultra once -it took a mound to bitter it, and flavor addition at 10 minutes was less, but this hop just burns in my flavor/aroma space part of my mind with no other equal. There is little fruitiness in Ultra, so it does well with traditional beers.
And they are resistant to disease which is the main focus to growers as well.
IMO, pushing these high alpha fruity girly hops will make growers forget to grow the traditionals. They will grow what sells.
I guess it's apparent now that I favor traditional beers/ingredients -so be it.
EDIT: I didn't first wort hop the Ultra, as it is not a high alpha hop. I only FWH high alpha or assertive hops -this may have been a big part of the equation!