Whilst all of the girls (Kiyone and Mihoshi included) enjoying a relaxing bath in the extra-dimensional bathroom, Tenchi and Nobuyuki are still stuck with using the regular bathroom. Much to Nobuyuki’s frustration, they can hear everything the girls are saying- but no matter what he does, there is no way for him to get in and see anything.
Wearily telling his father to give it up, Tenchi sinks down into the bath, only to find that it suddenly goes much deeper than before. Suddenly underwater, Tenchi and Nobuyuki swim for the surface- but whilst Tenchi makes it into the girls’ bathroom, poor Nobuyuki somehow ends up in the kitchen sink.
Clearly, something has gone wrong with the extra dimensions around the house, and everyone decides to pay Washu a visit to find out what is going on. Washu explains that what happened is most likely a result of her tinkering with the dimensional tuner- a new invention that is able to create a reality based on the user’s needs and desires. On hearing what the dimensional tuner does, both Ryoko and Ayeka are eager to give it a go (what better way to guarantee a life with Tenchi?), but Washu forbids them. The machine is unfinished- and strictly off-limits.
Reluctant to return to the apartment after having gotten behind on the rent, Kiyone and Mihoshi decide to stay the night, and soon everyone is fast asleep- or so it appears. Having only feigned sleep until everyone else was in bed, Ryoko quietly gets up, hoping to get a shot at using the dimensional tuner whilst no one else is around. At first, it looks like her luck is in- the lab is empty, and Ryoko is able to begin entering the settings for her ideal world.
Unfortunately for Ryoko, she wasn’t the only one with that idea, and soon all of the other girls show up in the lab- each wanting to use the dimensional tuner. Soon, everyone is trying to input their data, and the influx of conflicting desires set the dimensional tuner on overload.
Awoken by all the noise, Tenchi, Nobuyuki and Katsuhito come in to see what is going on, shortly followed by Washu, who was working in another of her extra-dimensional rooms. Seeing that her precious machine is about to explode, she tries to deactivate it, but to no avail. Quickly retrieving the dimensional tuner core before it gets destroyed, Washu warns the others that they will soon be drifting through multiple realities, possibly for the rest of their lives. Their only hope is for Washu to somehow find a way to fix the dimensional tuner as soon as possible.
As the machine finally explodes, everyone finds themselves moving through a nexus of time and space, finally emerging in an alternate reality resembling Heian era Japan. In this reality, Tenchi is a brave warrior, whilst Ayeka is his devoted fiancée. When Tenchi has to leave to destroy the demon of Rashomon, a worried Ayeka persuades police officers Kiyone and Mihoshi to go after him, promising Kiyone the promotion she wants so much if she fulfils her task.
Even as Kiyone drags the reluctant Mihoshi to Kyoto, Tenchi is meeting with the demon Ryoko- not to kill her as he ordered, but because she is his secret girlfriend. Tenchi warns Ryoko that he has been ordered to kill her, and she suggests that they run away together. But as Ryoko starts cuddling up to Tenchi up on the roof of a building, they are discovered by Kiyone and Mihoshi.
Fortunately, Kiyone is easily persuaded to remain silent about the whole matter (she doesn’t want to provoke Ayeka’s wrath either), and she assures Tenchi that Mihoshi will keep quiet as well. Unfortunately, even as they talk outside, Ayeka has arrived to see her beloved fiancé, and whilst they were waiting for Tenchi to come inside, Mihoshi told her everything!
Kiyone and Tenchi quickly smooth over the damage by claiming that Mihoshi is just making up stories, but even as Ayeka seems about to reluctantly accept this, Ryoko arrives. She couldn’t wait to see Tenchi again, and now it is time to run away together just as they planned.
Ayeka is furious to see Tenchi with another woman, and soon she and Ryoko are arguing over him just as they would in any reality. Meanwhile, still in the time and space nexus, Washu tinkers with the dimensional tuner, and realises that she has only one choice- she must systematically eliminate all of these extra realities.
Brandishing a kwan dao, Ayeka goes on the attack, and soon both she and Ryoko are trying in vain to defeat one another. Whilst the others unsuccessfully try to break up the fight, Washu sets up an enclosed dimension to work in, and inputs the order to cancel the first reality. As the Heian era world disappears, Tenchi and the others find themselves falling through time and space once again, but just where will they end up next?