The contents of the Masaki family shrine have always been of great curiosity to teenager Tenchi Masaki, and one summer he decides to investigate it for himself- that is, if he can find where his grandfather Katsuhito has hidden the keys. No stranger to Tenchi’s fascination with the shrine, Katsuhito is already one step ahead of him- he keeps the keys safely secured on his person. After catching Tenchi searching through his room for them, Katsuhito offers him a deal- Tenchi can have the key, but only if he manages to take them from his grandfather.
The law of the Masaki shrine is that no one may enter, and Katsuhito is confident that Tenchi will not be able to take the keys. Launching himself at his grandfather, Tenchi gives it his best shot, but Katsuhito easily blocks him. With a few easy moves, Katsuhito knocks Tenchi crashing into a wall screen, and confidently leaves- it looks like Tenchi needs to train some more. What he doesn’t realise, however, is that Tenchi is better than he thinks- the young man managed to snag the keys with his mouth.
As soon as possible, Tenchi rushes off to the shrine, preparing to satisfy a curiosity that has plagued him for years. Even as a little boy, Tenchi would come up to the locked gate of the shrine and wonder about what lay in the cave within. Katsuhito eventually explained to him that, generations ago, a demon came from the stars and began terrorising the Earth. One of their ancestors, a samurai named Yosho, also came to Earth, and fought the demon using a great and powerful sword. Now, the demon sleeps, trapped in the shrine, with the sword watching over it.
Now, after all these years, Tenchi can finally enter the shrine and find out the truth of the legend from himself. And indeed, as he makes his way inside, he soon finds that the story is at least half-true, for within a special wooden “mini-shrine” he finds the legendary sword itself.
The years have not been kind to the sword, however, and when he draws it from its scabbard, Tenchi discovers the weapon has become rusted and useless. Disappointed, Tenchi slashes at a rock, and to his distress, the blade shatters. Amazingly, though, the rock he targeted splits in half, and soon other rocks begin moving around, exposing a crack that leads deeper into the shrine.
Still holding the hilt of the broken sword, Tenchi heads further into the shrine, and ends up slipping down a long slope into an underground chamber. At the centre of the chamber is a glowing well, and as Tenchi gets closer, he sees that the glow isn’t coming from the well itself, but from a mummified body- clearly the sleeping demon is more than just a legend.
A little unsettled, Tenchi drops the sword hilt, and as he goes to retrieve it, the demon suddenly reaches up and grabs him. Rising from the water, the mummified demon caresses Tenchi’s cheek, and as Tenchi struggles to escape, it leans forward as if to kiss him. Fortunately for him, a blue light comes between them and throws them apart, giving Tenchi the opportunity to make his escape.
Climbing out, Tenchi quickly uses a vine to tie together the halves of the split rock, and the crack closes up again. Hastily leaving, Tenchi decides to return the keys as soon as possible- hopefully this will be the end of the matter. What he doesn’t know is that his actions have activated some kind of a beacon- the large tree outside the shrine has started sending a beam of energy into space.
By the end of the summer holidays, Tenchi has nearly forgotten his escapade at the shrine; Katsuhito never said anything about it, and the normality of being back at school soon wipes it from his mind- at least until his friend Amagasaki makes a chance comment about mummies.
Reminded of the incident, Tenchi lies down outside between classes to think about it, only to end up falling asleep. By the time he wakes up, it is dark, and everyone has gone home- everyone that is, except a mysterious green-haired young woman. As she introduces herself as Ryoko, her eyes glow green, and a horrified Tenchi realises that she is the demon from the shrine.
Having been locked in the shrine for seven hundred years, Ryoko is more than a little pissed off, and decides to take her frustration out on Tenchi. With one hand, she forms a glowing orange energy sword, whilst with the other, she begins firing orange energy blasts at poor Tenchi, wrecking the school playground in the process. Unable to run away fast enough, Tenchi decides to try fighting. Searching through a pile of wreckage, he grabs a piece of broken pipe, and attempts an attack. Laughing, Ryoko easily repels his first attack, and when Tenchi tries again, she slices his pipe into pieces.
Running away, Tenchi manages to make it inside the school, only to fall down the stairs as soon as he gets indoors. Gathering himself up, he scrambles down the corridor and finds a classroom to hide in. Teleporting herself from point to point Ryoko follows after Tenchi, but to his relief, she moves right past his hiding place.
Tenchi’s relief is short-lived, however, when he realises that Ryoko’s rampage has caused a gas leak. Tenchi decides that it is past time to get out of there, but unfortunately for him, Ryoko is still on his tail. Phasing through the classroom wall, she advances on Tenchi, energy sword in hand. With nothing to lose, Tenchi tries the “hey, look over there!” trick, and to his astonishment, Ryoko falls for it. Whilst Ryoko is distracted, Tenchi runs for it, and only a few seconds later, Ryoko realises that she has been tricked. Angry, she crackles with energy, and ignites the gas that has leaked into the room.
Thrown down the corridor by the blast, Tenchi concludes that Ryoko must have been burned to death in the explosion, and says a quick prayer for her. Ryoko is far from dead, however, and to Tenchi’s horror, she emerges from the fire almost unscathed. Terrified, Tenchi runs again, with Ryoko in hot pursuit- at least until she spots a mirror. Realising what a mess she looks, Ryoko stops to pretty herself up, and Tenchi takes the opportunity to slip away to his classroom.
After a quick rest, Tenchi collects his satchel and tries to decide what to do next. As the fire alarm finally goes off, Tenchi is at first startled, until the red glow of the alarm reminds him of something. Ryoko has a gem on her wrist, and according to the legend, that is the source of her power. All he has to do is remove it- surely it can’t be that difficult.
Now fully cleaned up, Ryoko has caught up with Tenchi once more, and she is ready to show him that beating her will be anything but easy. As she fires an energy blast at the classroom, Tenchi has no choice but to leap out of the window as the place goes up in flames- however, Ryoko is waiting for him outside, and soon corners him against the fence. As she slashes at him with her sword, Tenchi tries to block the blow with his satchel, and amazingly, a blue light appears to protect him. It is emanating from the broken sword hilt that Tenchi now carries around with him, and to Tenchi’s amazement, the hilt emerges from the satchel and floats in front of him, creating a shield that protects him from Ryoko’s next few energy attacks.
As Tenchi wonderingly grabs the hilt, Ryoko attacks with her sword again, but once again her blow is blocked- the hilt has begun projecting a blue energy sword. In Tenchi’s hand, the blue sword seems to fight back with a will of its own, driving Ryoko back. As the battle continues, Tenchi calls Ryoko a monster, and the offended demon knocks him back. Insulted by being called a monster, Ryoko launches an attack, but the sword once again responds, this time cutting off her right hand.
The severed hand vaporises, and Ryoko’s gem falls to the ground, where it too explodes. Tenchi apologises for removing her hand, but for Ryoko, it is no problem- using a little of her power, she quickly creates a new one. As Tenchi applauds, Ryoko takes a bow, before phasing into the ground and disappearing.
With the imminent arrival of the fire brigade, Tenchi decides that it is time to leave, and makes his way back home. Everything seems quiet, and a relieved Tenchi decides to get some well earned rest. As he lies back on his bed, however, he is in for a surprise. The bed seems a little lumpier than usual, and as he pulls back the covers, Tenchi discovers why- Ryoko is sleeping there! Waking up, Ryoko welcomes him home, and Tenchi once again says a quick prayer- this time for himself. Will things ever be the same?