So I was convinced that there were no pop/rock Japanese songs in anything but 4/4 BUT then I found out that a popular song that has been played to death and is common is actually in an odd time signature. And the song is... WIND by Akeboshi, the very first ending song of Naruto. http://www.youtube.com/watch?v=j5ORESglJAM The song is in 5/8 which is one of my favorite odd time signatures. So as a music theory geek, I thought this was interesting. I think there was another one but I can't remember what it is.

I noticed a few 'odd' ones by pop standards.

Clannad After Story's OP (http://www.youtube.com/watch?v=klUfRsd20gE) is supposed to be entirely 4/4 I think, but it gives the impression of being in 3/4 or even 6/8 before moving into the chorus.
Then there's Kannagi's ED (http://www.youtube.com/watch?v=FKcmGfzL2JI), which sounds like it's in free time for the first while. H2O Footprints in the Sand's ED featured a time change into waltz and then back in the full version, but I can't find a youtube video of it.