Oikawa has always been a loner, even when he was young. His only friend was Cody's father, Hiroki, who would spend hours playing video games with him. They both discovered that a Digital World existed, but never had actually embarked on a journey. As they grew older, Oikawa became a researcher and Hiroki followed the footsteps of his father by becoming a police officer. Unfortunately, he was killed in the line of duty and the strain of losing his best friend broke him emotionally.
When Tai and the others returned to the Digital World to fight the Four Dark Masters, he encountered the spirit of Myotismon who had just been defeated, and accepted his offer to become his host, in the hopes that he would eventually take him to the Digiworld. For three years, Myotismon manipulated him for his own purpose. He was responsible for sending Ken the mysterious e-mail and transporting him to Dragomon's Dark Ocean world, infecting him with evil, turning him into the Digimon Emperor. He also created Arukenimon and Mummymon from his own DNA, since he was human and unable to travel to the Digital World.
He appears in Season 2. All the Digidestined from around the world help defeat Malomyotismon and Cody rescues Mr. Owikawa. Mr. Owikawa is very badly injured and wishes he had Cody’s optimism and hope. Mr. Owikawa sacrifices himself to restore the Digital world. By transforming himself into energy he becomes part of the Digital world and is able to use his life force to revitalise the Digital world.
