Tenchi's mother is dead. Admittedly so far he's had three different mothers across the franchise, but the only one who wasn't dead was in Magical Girl Pretty Sammy and that doesn't count. In the OVAs she's grey-haired and confusingly called Kiyone, but that's only in the third series and the 20th episode. Everywhere else she's Achika. She's in Tenchi Universe (episode 9), Tenchi in Tokyo (episodes 7, 12, 17) and even Magical Girl Pretty Sammy (episode 10). In the latter she's an in-joke in a silly throwaway episode that we're not meant to be taking seriously, but she's alongside Tenchi's father and grandfather and I found it oddly affecting to see them together.

Achika normally only appears in flashbacks, but this is a time travel story. It's the Tenchi Muyo equivalent of Back to the Future and it turns Achika into a major player. Don't worry about the misleading title, by the way. Oedipal situations are fortunately absent, although for a while I was worried.

We start with a creaky home movie. That's all Tenchi really has left of Achika, who died young. He doesn't really have any memories of her, although he's heard stories from his father and seen a few photos. However soon he might not even have that. Something called Kain has escaped from the heart of Galaxy Police headquarters and time-travelled back to 1970. His target is Achika.

This film is a sequel to Tenchi Universe, but it's more like one of the dramatic closing episodes than the earlier knockabout comedies. Without Achika, it would have been unremarkable. Kain is scary, but the film's almost over by the time he shows up properly. The regulars aren't bad, but you're expected to know them already and they're not being played for laughs this time. Sasami and Ryo-Ohki in particular get little to do. Tch. No, this is Achika's show and she ends up taking centre stage and making choices that it's speculated might have contributed to her own death. She's what makes this a strong story. At one point I was bracing myself for a "technobabble saves the day!" solution, but in the end it was much more dramatic. Act Three is where the film really picks up, which was doubly surprising for me since for a while I'd been expecting them to wrap things up with Act Two without even extending it to a third act in the first place.

Anime movies are rubbish, you see. There are a few obvious exceptions to this rule, but in particular a big-screen version of a TV series will tend to be a reboot, a ham-fisted compilation or an outright violation of its source material. However this is a solid piece of work with no real flaws. Its pace is gentle, but at least it's writing to its length rather than floundering around because its scriptwriters don't know how to write to anything except the 25 minute format. Okay, not much happens in Acts One and Two. Once the Tenchi crew reach 1970, they're basically just watching and waiting. However the characterisation is intact. Ayeka and Ryoko are their usual bitchy selves and Mihoshi is still brainless, even if the film wants to be dramatic rather than fluffy.

Admittedly I'd expected more comedy disasters. Ayeka and Ryoko almost destroy a train while having a tiff, but that's small potatoes by their standards and the only surprise is that it still managed to reach its destination.

The animation does everything right, preserving the original character designs while looking as pretty as a movie should. What's more, it uses its visuals. Changes in art style underline the narrative. The characters and their contemporary world are faithful to the look of Tenchi Universe, but then travelling back to 1970 takes us to a world of beautiful painted backdrops, luscious autumn leaves and an explosion of Technicolour. They're evoking the old-fashioned animation style of movies of that vintage. It's both charming and clever.

Curiously enough, the cast tend to adopt the roles they took in the Pretty Sammy OVAs. Mihoshi is a teacher, Ayeka and Ryoko are schoolgirls, etc. We also get to see Kiyone in the bath. However the most important character is Achika. Our heroes' job is to keep her alive and see that she marries Tenchi's loser of a father, even if she isn't going to be around for long to enjoy her life with him. She reminds me of Tenchi in Tokyo's Sakuya, incidentally, which is either sweet or a little creepy if you think about it.

This film rises slightly above the frivolous bubblegum level of much Tenchi Muyo, in the end having a tinge of melancholy. It's charming. Add this to the list of good anime movies! It's decent rather than brilliant, but it's true to its source material while having a heart and a soul.