You have got to hand it to the Japanese for over complicating everything. These awesome drain covers are no exception.
There is a massive geek following for these covers in Japan, to the extent that they get stolen a fair bit too. I can tell you, that would never happen in the UK. Geektastically, the finest drain covers are even highlighted on Google Maps.
Why the hell not decorate them? There HAVE to be drain covers, so why not make them as beautiful as possible?