It's kind of a showcase of Japanese culture: food (included in ticket price) (reputed to be good bentos, unfortunately as I am involved I won't get any), dance, fashion, music. I haven't been before, but it's a popular event (~400-500 people) and I've been to the annual Luau put on by the Pacific Islanders club (which is a similar event) and it was a blast. Tickets should be available through the PSU box office, though I don't have better details with me.
The JSS (student club putting on the event) has a lot of Japanese exchange students as well as anyone interested in Japanese culture, and has "contribute to world peace" in the mission statement. (I also saw "we are not the anime club" in some of the literature they had, if that gives you a better idea of what the club is about, and what kind of event they'd put on.)
I'm flying into PDX right around then to do some on-site work, and one of my Bachelor degrees is in Japanese (though not from PSU).