Retired scientist Tokunoshin Oomori has spent years alone on a remote island chasing a breakthrough in time-travel research, until the self-proclaimed elite space cop Jaco crash-lands his ship right next to his house. Jaco insists Earth faces an incoming alien threat, but his bragging rarely matches his competence, and he moves in with Oomori while his ship is under repair. Akira Toriyama's story is set before Dragon Ball, tying Jaco into that universe's earliest timeline.