GINTAMA
The story takes place in Edo (known today as Tokyo because of the name change in 186 cool , Japan, which has been taken over by aliens called Amanto since the late Edo period. The samurai of Japan have fallen, and the Amanto placed a ban on carrying swords in public. The story focuses on an eccentric samurai, Gintoki Sakata, his (partial) apprentice Shinpachi Shimura, and a teenage alien girl: Kagura. All three are "free-lancers" who search for work in order to pay the monthly rent, which usually goes unpaid anyway.
Source: Wikipedia
