(First Aired: November 27, 1966)
Screenplay by: Tetsuo Kinjo
Directed by: Yuzo Higuchi
It begins one night at Ohmuroyama Zoo in Izu when the night zookeeper reports about inexplicable rumblings and flashes of light from the hilltop overlooking the place to Science Patrol. Muramatsu, Hayata, and Arashi head out immediately. At HQ, Fuji is visited by a young boy, who does not respond to her questions. What does come out of the boy’s mouth is a strange message – "The dragon Hydra will appear at Ohmuroyama Zoo and attack". The boy leaves the room without further word. Then Ide enters the room and when told about the boy who just left the room, Ide tells Fuji he didn’t see any kid come or go down the hall. The guards in HQ’s gates haven’t seen any unpermitted children either, and even if one snuck in, the alarm should have activated. Back at the zoo, the men are skeptical of the report, though they are informed that half a year ago, every tree on the hilltop inexplicably died, as well as the recent panicked behavior from the zoo’s animals. Fuji reports the boy’s prophecy to Muramatsu through the communicators, suggesting they should investigate for a little longer just in case.
At the front of the zoo, the zookeeper shows the men a big stone statue of a monster resembling a bipedal griffin with a dragon’s rear quarters. He tells them that the statue is of Hydra, a monster created for a children’s contest to honor the zoo’s opening. Hydra was created by an elementary-aged boy from Tokyo named Akira Mutou, who lives at Akebono Boy’s Home. Hearing it through the communicators, Fuji jots down the address before taking Ide on a trip to Akebono. At the orphanage, the two learn that Akira was killed half a year ago when a car ran over him on Route 87. They also learn from the headmistress that Akira was very fond of animals, especially mountain birds, and he drew many pictures of Hydra, a monster that Akira frequently daydreamed about. Fuji then notices among Akira’s Hydra paintings, a picture in memory of him and recognizes his face. Akira is the strange boy who visited her at HQ!
Night falls over Japan, and Muramatsu, Hayata, and Arashi remain at Ohmuroyama Zoo. They are about to give up their search when they witness the hilltop flashing and rumbling as if an invisible thunderstorm had suddenly appeared over it. The rumblings increase in strength, and the hill cracks open like an eggshell. Then, Hydra steps out of the hill, resembling exactly like the statue at the zoo and the bird-beast Akira imagined. The feathery dragon spreads its wings and takes off. The stunned men then head back to the Jet V-TOL in pursuit, but Hydra leaves the area too quickly for them.
While the team reunites at HQ and plans out their next move, Hydra soars across the Japanese countryside. The monster makes a beeline for Route 87, where it smashes every vehicle it sees like a reckless child does with toys. Science Patrol comes in on the Jet and Mini V-TOL, after receiving a report on Hydra’s location at the outskirts of Tokyo. Hydra is soon located and fired upon, but Hayata and Arashi in the Mini V-TOL crash in a near collision with the bird-beast. Both survive, but Hayata sustains an arm injury, taking him out of the monster hunt.
Science Patrol decides to switch tactics by having Arashi drive a gasoline truck down Route 87 as bait while the Jet V-TOL follows. Hydra appears, and Arashi gets out to take an opportunity to fire at the truck while it lies in Hydra’s claws. The resulting explosion injures Hydra, but only enough to make it chase Arashi. Meanwhile, Hayata sneaks away from his resting place, despite having his arm in a sling, to become Ultraman!
Ultraman immediately takes off to Hydra’s location and proceeds to wrestle the monster. Hydra proves to be quite ferocious and pummels Ultraman with ease. Then quite suddenly, Hydra takes off to the sky, dodging a Specium Ray and leaving Route 87 behind. As Hydra flies higher and higher, Science Patrol and Ultraman spy the most curious thing – Akira’s ghost riding atop Hydra’s back before vanishing. As Hydra disappears from sight, Ultraman decides not to pursue and leaves. After the battle, Science Patrol stands in front of the Hydra statue in remembrance of Akira at Ohmuroyama Zoo, pondering if Hydra had appeared to avenge the death of its creator.
