Regrettably, despite being one of my most favourite Japanese folklores, I obviously didn't exactly remember it well enough to have designed a theme in time for it. Though, I did come across an amazingly beautiful image of Tanabata today:
For those who are curious about the specifics, the illustration is actually derived from an otome game by Rejet, Ken ga Kimi.
Maybe I'll put it up as my Tanabata theme for next year.