Some anime series are wildly popular, spanning decades in the form of TV series, movies, OVAs, and an ocean of tie-in projects. Others burn bright, but wrap up after a single TV series or film. But there are a few - just a handful, really - that never really go away. Most of them are family comedies or kids' fare, like Sazae-san, Chibi Maruko-chan, or Doraemon. In the realm of science fiction anime and manga, there are a handful of stalwarts that have been hanging around for deades, mostly thanks to the fastidiousness and dedication of their creators - open-ended classics like Locke the Superman and Five Star Stories. What is it, I wonder, that makes a series hang in there and retain an audience for that long?