Yuichi works for a logging company in Hokkaido that is often under "attack" by environmentalists. It is Yuichi who puts the plot of the film in motion by removing the Seal of Elias from a shrine that was discovered in one of the company's forests as a gift for his daughter. The discovery of said shrine causes a media uproar that forces Yuichi to return to the work site shortly after returning to his home. When Yuichi is at the site, he is possessed by Belvera, who forces him to take the company's dynamite and blow up the shrine to release Desghidorah.
Yuichi and his family are taken to a local hospital after Mothra is defeated, where they receive treatment for wounds sustained while searching for each other in the forest where Desghidorah resided. Yuichi is seen again at the end of the film, re-united with his family. While Yuichi's children are riding Mothra Leo, Yuichi and his wife discuss the environment and what people can do to save it. Both agreeing that it may not be in their lifetime.
Yuichi is shown to be level headed and caring. Even though he is not always at home with his family it is clear that they all still care very much about each other. It is Yuichi's belief that the waste of paper is wrong. Even when he is reminded that he makes his living making paper, he claims that that is not a reason to waste it. Yuichi believes that the environment can be saved by hard work and effort.