21st Century Security has a new, influential and well-paying client- Master Sakuraou Taikai, a religious fanatic who claims to be the only man who can understand and combat the Heterodyne. The presence of Dai-Guard at his talks seems to endorse his claims, and despite Shirota’s disgust at the situation, Nishijima and Saeki are willing to play along.
Shirota has little love for this new regime- the new pilots are little more than an accident waiting to happen, and PR Division 2 seems to be spending its last day together doing little more than moping. That is, until quitting time, when everyone suddenly becomes energised and happy as they grab travel bags and leave. Shirota is confused as he and Kamimura observe this sudden change in attitude, but Kamimura recalls that the members of PR Division 2 have decided to take one last vacation together before their division is dissolved.
Together with Yokozawa’s daughter, the team are travelling to the Kyoto area to stay at the Yokozawa family’s mountain retreat. On the train there, Akagi is busy looking after everyone else, until Ooyama convinces him to relax and have a few beers; after all, he was the one who had to stay sober during all the Heterodyne alerts. As Akagi warns them, however, he isn’t a very good drunk, and indeed, by the time the team are making the walk up to the retreat, an overly talkative, blind-drunk Akagi has to be half-carried up the mountain by Aoyama.
Sumida and Yokozawa’s sister are waiting for them at the retreat, and already something has gone wrong- Yokozawa’s father has gone missing. Ever since his wife died ten years ago, Mr Yokozawa has been increasingly distant and bedridden, so his sudden disappearance seems very strange.
Everyone joins in the search for Yokozawa’s father, who is eventually found outside, sitting on the cold ground and talking to a hill. Irie is the first to notice that is no ordinary hill- some of the upper soil has been scraped off the reveal the distinctive hexagon pattern seen only on the body of a Heterodyne.
Although the others haven’t yet decided what to do about the Heterodyne’s presence, Sumida decides to put in a quiet call to his beloved Domeki to let her know about it- after all, she likes that kind of stuff. With the help of her computer, Domeki deduces that the Heterodyne must have been created during a series of quakes that occurred ten years ago. It has been lying dormant ever since.
Unaware that Sumida has already told Domeki about it, the team gathers to discuss whether or not they should tell anyone about the Heterodyne. Whilst Akagi sleeps off his hangover, the others vote, and to Ibuki’s concern, everyone else is happy to keep quiet about the monster’s presence. Bringing the army in would only ruin their vacation, and besides, they can always keep a watch on it just to make sure it stays inactive.
Despite the fact that most Heterodynes appear near the Pacific Ocean, Taikai has convinced Saeki to bring Dai-Guard to Kyoto. He wants to robot’s presence to enhance his image there, and things would look even better if Dai-Guard were to actually battle a Heterodyne whilst there. An annoyed Shirota remarks that Heterodynes do not appear so conveniently on demand, but in this case, Domeki begs to differ. Having ignored Sumida’s pleas to keep it quiet, Domeki discloses the location of the Kyoto Heterodyne, and even brings the Knot Punisher along so that Dai-Guard can finish it off.
Waking up the next morning, Ibuki looks outside to see Akagi challenging the Heterodyne. To her horror, the creature activates, and surges out of the tree to take on a vaguely humanoid form. Whilst Akagi is drowned in displaced earth, the Heterodyne grows ever bigger and reaches out for Ibuki, who screams at it to stay away…
Fortunately for Ibuki, that was all just a nightmare, but her concern over the Heterodyne is very real. The men were supposed to be watching it overnight, but predictably, they fell asleep, and now Akagi has found out about the Heterodyne’s existence. The others are sure that Akagi will not want to keep quiet about it, and Ibuki can’t help feeling that maybe this is for the best.
But it seems that there is no need for anyone to keep anything quiet anymore- thanks to Sumida, Saeki and Dai-Guard have already arrived. Taikai has come along as well, seeking to earn publicity by ‘smiting the evil beast’.
Despite Shirota’s objections, Saeki has Makise and the others launch Dai-Guard. As the robot heads over to the Heterodyne, Ooyama realises that they should probably evacuate and get to safety. Akagi, however, does just the opposite- instead of leaving, he steps right into Dai-Guard’s path. Yokozawa’s father and daughter join him, shortly followed by the rest of the team, and Dai-Guard is forced to back off.
The others are confused about Akagi’s defence of the Heterodyne, so he tries to explain his reasoning. For some reason, Mr Yokozawa thinks the Heterodyne looks like his deceased wife- he believes she has returned to him, and Akagi doesn’t want to shatter the old man’s illusion. Ibuki and Yokozawa agree that attacking the inactive Heterodyne will probably do more harm than good, and convince Shirota to only take action if and when the Heterodyne activates.
Not everyone is happy with this, however; Taikai is determined to boost his publicity by being present a Heterodyne battle, and Saeki seems inclined to accommodate him. To that end, he has Makise and the others activate the Drill Arm, in the hopes that its high frequency vibrations will awaken the creature.
Rushing over to find out what is going on, Akagi confronts the three new pilots. When the pilots comment that destroying Yokozawa’s home and endangering innocent lives is less than important to them than being seen as heroes, Akagi gets angry. Rushing towards them, Akagi seems ready to start a fight, only to get knocked down immediately when one of them elbows him in the stomach. Even as they gloat, however, Shirota gives them a little retribution- by punching each pilot in the face.
Meanwhile, aroused by the Drill Arm, the Heterodyne rises up out of the earth to form a huge hill of its own. Makise and the others decide it is time to head out in Dai-Guard, but Shirota won’t let him. The only pilots he is willing to depend upon for this mission are Akagi, Ibuki and Aoyama.
Powering up Dai-Guard, Akagi and the others leave the Knot Punisher behind- Akagi has a different plan for taking on this Heterodyne. Walking up to the hill, he begins pushing down on it, revealing to the other pilots that this is the extent of his plan. Everyone is sceptical about what good this will do, but to their surprise, after a little while, the Heterodyne begins sinking back into the earth, inactive once again.
After the battle, Domeki shares the results of her Heterodyne analysis with Shirota. The creature was created ten years ago, and now lies under the entire Kyoto area. Destroying it or fully awakening it would only cause the entire region to collapse, resulting in the destruction of Kyoto itself. The only thing they can do is leave the Heterodyne where it is, and as it seems to be slowly sinking deeper into the earth anyway, in a few hundred years it will be dissolved as it enters the mantle. It may not seem like a victory in a decisive sense, but as he watches PR Division happily working outside, Shirota realises that for them, at least, this one counts as a win…