Tenchi Muyo! in Love (天地無用! IN LOVE, Tenchi Muyo! in Love?) is the first of three movies set in the Tenchi Muyo multi-verse.

The film takes place after the conclusion of Tenchi Universe, and so varies from the original OVAs at several points. Most noticeable of these is the inclusion of Achika as Tenchi's mother instead of Kiyone Masaki.

The movie was followed by Tenchi Muyō! In Love 2 - Haruka naru omoi (Tenchi Forever! in the US), released in 1999.

As the movie began, the A-1 class criminal Kain had escaped confinment in the subspace room of the Galaxy Police Headquarters, then succeeded in destroying G.P.H.Q.. However, before its destruction, headquarters sent out an emergency message, warning of Kain before cutting out.

Almost immediately, things started going wrong. Tenchi Masaki shows all indications of fading out of reality altogether, as well as the house and shrine becoming aged ruins. Washu, picking up subspace indications of what's going on, places a temporal shield around Tenchi. However, the shield is only temporary, so now Tenchi and the girls have to find out what Tenchi's mother Achika has to do with what's going on.

Source: Wikipedia