The focus is always on the young Tenchi Masaki, who one day inadvertently rescues a space pirate from a cave in a distant galaxy. From then on, all sorts of funny situations arise in which many other space travellers also appear on the scene.
In the first film, super criminal Kain, a powerful and monstrous creature, escapes from the custody of the Galaxy Police. He now demands revenge on the Imperial family for his imprisonment. For this reason, he travels back in time to kill all the descendants. His first victim is to be Achika - Tenchi's mother. Tenchi also notices the workings of Cain when he temporarily disintegrates again and again. To save his parents, Washu finally uses her time machine and sends Tenchi and his friends back to 1970. During a trip by Achika's class to the television tower in Tokyo, they finally meet Kain and the battle for the future of Jura begins...