During Godzilla, Kyohei's presented as very formal in attire, generally wearing suits to the many meetings he's present at. At home, he was also seen wearing white laboratory coats. For many parts of the film, he also wore glasses.
Kyohei was portrayed as intelligent, and faithful to the cause of science, having been at the forefront of any scientific investigation into Godzilla, during the film's events. Sometimes, to his own detriment, as he handled a Trilobite with his bare hands, something that was later revealed to have been doused in Strontium-90, following Godzilla's movements through the area.
He also became very downtrodden once plans to kill Godzilla were put into motion, as he felt the creature should be studied over destroyed, even in spite of the risks.
Yamane also had a strong conviction against nuclear weaponry, believing their testing and use could awaken another Godzilla, an event he turned out to be correct on.
During the investigation of Odo Island, Dr. Yamane visited the grave of Masaji Yamada and his mother, victims of Godzilla's raid, and met Masaji's younger brother Shinkichi. Yamane later adopted Shinkichi as a son.
Serizawa and Yamane shared little screentime during the events of the film, but Kyohei expressed clear shock and sadness at Daisuke's decision to commit suicide during the film's final act, even taking off his hat as an act of respect.
Following the devastation of the Odo Island village, Yamane was invited to a special session of the Diet to hear accounts by survivors and give his thoughts. He recommended a investigative party be sent to the island, and subsequently headed the party. On Odo Island his team discovered that areas in the wake of the destruction had been exposed to massive radiation; these areas had been pounded with a trail of holes in the ground, which Yamane identified as footprints of a large creature. In one of these footprints he also discovered a well-preserved trilobite. The investigation was interrupted by the sudden reappearance of the creature beyond a hill. Yamane took several photographs before fleeing with the islanders; the creature soon retreated into the ocean, leaving a new trail of footprints.
Immediately upon the return of the investigative party another Diet session was held, at which Dr. Yamane presented his findings, including the trilobite and sediment from the footprints dense in Strontium-90, a byproduct of hydrogen bombs. Yamane identified the creature as an intermediary (land- and sea-going) dinosaur from the Jurassic age, based on carbon-dating the sediment and named it "Godzilla," in accordance with an Odo Island legend. He concluded that modern atomic tests had awoken the creature, and that in having survived exposure to atomic weapons it would be extremely difficult to subdue.
Yamane was consulted by the government and the military for the duration of the crisis, though his personal conviction was that Godzilla, the only known survivor of the atomic bomb and therefore a wealth of knowledge (and hope for a cure to radiation sickness), should be extensively studied while alive. Following the destruction of Godzilla by the Oxygen Destroyer, Yamane expressed concern that further atomic testing may awaken another Godzilla in the future.
Dr. Yamane was summoned by the Japanese government to offer advice on how to deal with Godzilla after two pilots had reported seeing a second Godzilla and the monster Anguirus on a deserted island. Yamane regretfully stated that there was no known way to stop Godzilla following Dr. Serizawa's death, but offered advice that Godzilla was enraged by light, which reminded him of the atomic bomb, so he could be repelled from Osaka by keeping the city in darkness and luring him out to sea using flares.
Dr. Yamane does not physically appear in Godzilla vs. Destoroyah, and is implied to have passed away long before the film's events, however he is mentioned several times and is seen in a photograph with his adopted son, Shinkichi. Emiko still lives in her father's house, and Dr. Yamane's office is shown in the film as well, and still looks identical to how it did 40 years ago.
List of appearances
- Godzilla vs. Destoroyah (Mentioned only, seen in photograph)
- Godzilla, Mothra and King Ghidorah: Giant Monsters All-Out Attack (Seen in photograph)