I think the first time I saw them as something some one had randomly pulled into a livejournal rpg. (I don't recall which one, but the context was "a school festival" and Fuji was involved. I think the only reason I was looking at it was that school festivals amuse me.)

Then I saw them on the t-shirt of a girl I randomly ran into.

They just kept popping up occaisionally.

I think they multiply.