Dr. Daisuke Serizawa, played by Akihiko Hirata, is a character in the 1954 film Godzilla.
Dr. Serizawa is war veteran and a scientist who is secretly working on an oxygen destroying weapon. He demonstrates it to his fiance Emiko Yamane in private, swearing her to secrecy. Within moments it kills the fish in the test aquarium, turning it to bones. She is disturbed by the experiment and leaves.
After Godzilla destroys large parts of the city, causing innumerable casualties, Yamane tells her new love interest, Hideto Ogata, about Serizawa's invention. Emiko and Ogata go to Serizawa to convince him to use the Oxygen Destroyer but he initially refuses, explaining that if he uses the device, the superpowers of the world will surely force him to construct more Oxygen Destroyers for use as a superweapon.
After watching a program displaying the nation's current tragedy, Serizawa finally accepts their pleas. As Serizawa burns his notes, Emiko breaks down crying. A navy ship takes Ogata and Serizawa to plant the device in Tokyo Bay. After finding Godzilla, Serizawa unloads the device and cuts off his air support, taking the secret of the Oxygen Destroyer to his grave. Godzilla is destroyed, but many mourn Serizawa's death.