Gintama

The title "Gintama" (or "Gin Tama" in the west) literally means "silver soul" which may sound like a standard cool title, but it plays with a more common vulgar slang in Japan when spelled slightly differently—kintama, or "golden balls"... another way of saying family jewels.

The land of the samurai. There was a time, long ago, when our country was called by that name. Those dream-filled blue skies upon which the samurai once gazed are now filled with ships from strange worlds...

The series is set in an alternate Edo period where the country had been taken over by aliens called Amanto, an allegory to the real life event where the Black Ships of the Bakumatsu years forced open Japan's doors for trade. Technology advanced greatly as a result, creating a juxtaposition between the Edo period and the modern period where current trends and people (at the time of writing) could be a part of the story.