Jiji is currently imprisoned at the Astronomy Research Institute, though he didn't start out there. He was originally a ninja from Sunagakure who took on a very different kind of mission when the Prime Minister of the Land of Redaku came through on a regional tour. Seeing potential in him, the PM hired Jiji to travel to Redaku and train up an entire army—a significant task for a historically peaceful country with zero combat background.
Once in Redaku's capital, Jiji was set up in the royal palace and assigned a palace maid named Margo to look after him. The two fell in love over time, and Jiji eventually decided to walk away from being a ninja altogether to be with her. By the time of the Sasuke Retsuden events, they'd reunited, and both ended up accompanying King Nanara to the Astronomy Research Institute, where Jiji even gave a tour of the facility while Nanara figured out how to revive it.
Content compiled by AnimeList.moe from publicly available sources.
