When the criminal Kain escapes from prison, he destroys Galactic Patrol Headquarters, then moves to Earth to strike the Masaki family, whose link to the royal family of Jurai engenders his hatred. Capable of moving through time as well as space, he plans to kill Tenchi's mother, Achika, before she marries his father, Nobuyuki. If Kain were to succeed, Tenchi would cease to exist, the Masaki line would end, and his friends would disappear.

Scientific genius Washu transports Tenchi, Jurai princesses Ayeka and Sasami, space pirate Ryoko, Galactic Patrol officers Mihoshi and Kiyone, and cabbit Ryo-Ohki back to 1970 to defend Achika. The inevitable wacky contretemps occur--Ayeka and Ryoko get into a fight that brings Tokyo's commuter train system to a halt--and it's interesting to see Nobuyuki as an uncertain architecture student, rather than a comic lecher. The final confrontation with Kain takes on an unusual poignancy from Tenchi's feelings for the mother he never knew (she died while he was an infant).

Unrated; recommended for ages 10 and older for brief nudity and cartoon violence. --Charles Solomon