From Yu-Gi-Oh!

Dr. Fudo is Yusei Fudo's father and husband of Mrs. Fudo.

He was the lead developer within R.R.D.'s Enerdy Reactor who was killed in the Zero Reverse effect. His leading position of R.R.D. was due to the fact that he was the leader behind the research into the "Planetary Particle", which 17 years ago was the particle needed for the development of the Enerdy technology.

This research consisted on the planetary gear which is one that is able to bind particles to others. Dr. Fudo named his son, Yusei Fudo, in honor of this particle, which is named Yuusei Ryuushi, as he wanted his son to be able to bond people together.

Rex Goodwin mentions him just before Yusei and the others are about to travel to Satellite aboard a helicopter. He tells Yusei that he and Roman Goodwin, Rex's older brother, were Dr. Fudo's head assistants.

Later on Roman tells Yusei and the others that Professor Fudo wanted to cancel the Enerdy research, as he already suspected that its rotation was quite unstable. Furthermore, he realized that there might be an accident (as it happened, he was right). However, its proposed cancellation was rejected by the City, causing Professor Fudo to be removed from the project and replaced by Roman.

Soon after, Roman overrides the system leading to the Zero Reverse incident. Dr. Fudo's last act is to save his infant son, Yusei, by ejecting him from the Enerdy development area in an escape capsule immediately before he is killed by the negative energy explosion.

Later on Mina reveals to the Signers that Yusei's father entrusted the "Red Dragon Archfiend", "Stardust Dragon" and "Black Rose Dragon" cards to Goodwin, so that their correspondent Signer could seal the control units of the Enerdy Reactor. She says that he obtained them from Roman, immediately after he was released from the project. When Roman showed the four dragon monsters to Professor Fudo, including Ancient Fairy Dragon, Dr. Fudo took them and ran. However, he was attacked during his flight, so he dropped Ancient Fairy Dragon, similarly to how Uru dragged the dragon down with it as the spider was sealed in the Nazca Lines.

Dr. Fudo's spirit inside the Original Enerdy Reactor.

Dr. Fudo makes a brief appearance in the Underworld during the events of Episode 58 after Yusei falls into the light of the Original Enerdy Reactor. He saves Yusei, and brings him to a river in the underworld. (This is thought to be Sanzu No Kawa, a river that is thought to be the gate to the underworld in Japanese Mythology.) There, he tells Yusei something important, while fading away. Yusei tries in vain to follow and talk to him some more. Unfortunately, his father disappears, and Yusei returns to the Enerdy Reactor, unconscious, though he quickly awakens.