In Gojira, Dr. Daisuke Serizawa was a young colleague of paleontologist Kyohei Yamane, betrothed to his daughter Emiko Yamane, and friend to Hideo Ogata. He saw active combat during WWII, and lost his right eye in battle - his iconic eyepatch is worn to cover the empty socket.
After the war, Dr. Serizawa became a scientist who studied elements and their effects on other objects and organisms. He eventually discovered a new element - "micro-oxygen" - that could create a destructive chemical reaction that liquefied molecules by separating their oxygen atoms. Using this knowledge, Dr. Serizawa created a weapon known as the Oxygen Destroyer, but kept its existence secret from everyone, even Emiko and Ogata.
Shortly after the first sightings of Godzilla, Dr. Serizawa decided to reveal his secret experiments to Emiko when she visited his home. After shocking his fiance with the horrific effects of the Oxygen Destroyer, he swore her to secrecy, explaining that he knew that the world was not ready to know of such a terrible weapon. He remained in his lab during much of Godzilla's subsequent attacks on Tokyo, continuing his research.
Emiko soon returned to Serizawa's lab with Ogata in tow, hoping to convince her fiance to use the Oxygen Destroyer against Godzilla. Serizawa adamantly refused, maintaining that his weapon would only begin a new age of terror once the world saw what it could do. He briefly scuffled with Ogata in defense of his decision, but paused when he saw a report about the devastation Godzilla had brought upon Tokyo. Shaken by the utter destruction, Serizawa finally agreed to use his device, but warned Ogata that he would only use it once.
Unbeknownst to his friend and fiancé, Serizawa had every intention to make certain that the secret of his ultimate weapon would remain secret. He burned all of his micro-oxygen research and insisted that he accompany Ogata on the dive to find Godzilla and deploy the Oxygen Destroyer. When they found the monster on the seabed, Serizawa activated the device and watched Ogata return to the surface before cutting his own line and dying with Godzilla. With the only copy of the Oxygen Destroyer used up, his notes destroyed, and his own life at an end, Dr. Serizawa hoped to ensure that no one would ever discover the same terrible power he had just unleashed.
FilmographyGodzilla Generations and Godzilla Generations: Maximum Impact. Dressed in his climactic underwater gear, this giant-sized version of Serizawa is a bonus fighter who can be unlocked after completing certain other monsters all the way to the Tokyo level's three stages. He activates the Oxygen Destroyer as his special fighting move, which completely demolishes any structure or military vehicle in its striking distance. His eye patch also converts into a Maser Cannon.