Yeah... I have heard the meet ups are shoot and miss... are you signed up with meetup.com Booker? I used to do a Spanish meet up through them, we always got plenty of target language use. Meetup.com usually designates a moderator to help get things moving with the meetup.
Museigen: I would go check down by Uwajimaya/Kinokuniya in the International District (on... 6th, I believe), they often have local publications listing events. I can't specifically remember any bilingual publications though, you may have to put your Japanese to the test.
I can't really say that the Japanese population in Seattle is booming enough to have that many organized events, though. At least, it never seemed that way to me (not compared to the other Asian ethnic groups--south east, mostly). The UW has a pretty big sized Japanese Student Association (JSA), and they are very active, but unless you have a contact in the club, getting your foot in the door might be difficult.
The meet-up idea would be a really good way to meet people who might know the best way to get that foot in the door though.
What part of Seattle are you in?
..... heh, OK... nevermind, I just read your profile. Dude, just sign up with JSA on campus... they are really big. I didn't go to UW (Seattle U.), but just find out when their next meeting is and show up... They are a pretty nice bunch.