A somewhat insubstantial supplementary work, really, insofar as I suspect you don't need to watch this to follow the story. "Picture drama" basically means it's told through mostly still images, with some limited animation such as characters sliding into frame and camera zooms and pans. You could think of it as like an audio drama with some illustrations. It's only seven minutes long, so if you like the Tenchi Muyou! Ryououki OVAs and/or Tenchi Muyou! in general you may as well check it out, unless it just can't hold your attention without much animation. What's interesting to me is that the presentation is quite similar tothe way cutscenes are done in some video games.