In his normal human form Mr. Okawa is a good looking young man. As a Devil Beast, his form resembled something like a large man with a wolf-like head. His hair also grew in mass and a pair of small horns grew from his head making him resemble something like a traditional Japanese Oni Demon. Beneath his eyes were a series of lines resembling eye-lashes.
In his Devil Beast form, he had sharp claws, sharper teeth and super strength. His agility also became a lot more enhanced and was able to crawl across a ceiling from his grip alone.
On the outside Okawa was shown to act kind and caring towards his students. But in truth he was a brute that forwarded himself on his perversions, because of this he was described as a sly fox. He whored out his students against their wishes, and had no problem in killing and eating others. Shortly before he tried to assault Jun however, he showed some resilience saying he had always liked her, showing perhaps a bit of his character before giving to his inhibitions.
Mr. Okawa is first seen very early on in the story talking to Jun Fudo, he tells her to take the schools tennis club up to the mountains for a trip, which would ultimately lead into the events that cause her to become Devilman Lady.
A little later on, a young girl thanks him for helping her with her study so late after school, however he transforms and rapes her before then eating her. The next night He is seen in his Devil Beast form having caused havoc in a jewelry store, as he makes his escape he kills several policemen.
When Jun returns to teach at the school he greets her with open arms, which Jun greatly appreciates and thanks him. Though, shortly after one of the other teachers, Mrs. Satomi, advises her to be wary of him, saying he was hiding secrets from everyone. And, as if on que he is approached by Kimishima, one of the girls he was forcing to whore themselves against their will. Kimishima wanted to ask if she could stop doing it, but her fear of Okawa held her tongue. Okawa instead rapes Kimishima before leaving, saying he'll increase her wages.
Later that night, when the school had closed and Jun was working late, he arrives and transforms, with the intent to rape her before killing her. However at the same time Jun gets a visit from Lan Asuka who gives her a gun titled the BB Enzyme Gun, designed specifically to force humanity back into Devil Beasts. Lan then tells her that one of the schools teachers had transformed into a Devil Beast. Jun arms herself before hiding in the school showers. Okawa comes bursting into the showers, half transformed and starts to go through the stalls, at the same time Jun swings round with the gun and fires, but misses. Okawa lunges at her but she shoots again hitting his back, he avoids a third shot by jumping onto and clinging to the ceiling. He jumps down and knocks Jun to the ground and he moves in to take her, but instead reels back in pain clutching at his head. The effect of the anti-beast drug in the bullets had started to take effect.
Okawa screams and flees. Lan appears and tells her to follow him and ensure his defeat, but Jun says her job was just to take out the Beast, they argue briefly before Okawa returned, having turned back into his Devil Beast form and grabs Jun. Lan takes out a pistol and shoots him, causing him to drop Jun, and turn his attention to her. He knocks her to the ground and tears away her clothes before taking her, seeing the disgusting scene, Jun transforms grabs Okawa, before throwing him into the ceiling, the two fight and Jun breaks some of his ribs. Having regained her senses, Lan shoot Okada with the BB Gun, causing him to begin turning human again.
On his last legs, he smashes through the wall and flees again. He dresses into his clothes and contemplates over what had happened, a schemes to blackmail Jun over what he had seen. As he left however, Kimishima calls out his name, he turns only to be stabbed in the heart with a large knife. The girl then flees and his body is found by a pair of H.A. Troopers.
However he did not die, instead he was sent to the Samuelson Institute in America, where he is experimented on by Dr. Jason and other scientists. Conicidentaly whilst Lan Asuka is being shown around the Institute, Okawa manages to escape, he runs into Lan and the two immediately recognise each other, he transforms but a pair of Devilman security guards come running and knock Okawa out, taking him back to his cell.