|Relatives, etc.||Wife (Divorced)|
|Species||Human (Partially Parasite)|
|Occupation||Custodian at Hotel Baths|
|Anime debut||Episode 6|
|Manga debut||Chapter 14|
|English Voice||Mark X. Laskowski|
Mamoru Uda (宇田 守, lit. Uda Mamoru) is, like Shinichi, a human inflicted by a parasite .
He is very tall, has an average build, and is slightly overweight. His hair is kept neatly combed. He has black hair and brown eyes. Mamoru is shown to wear a vacation shirt in the manga, but in the anime he wears a jacket. When they briefly abduct Kuramori, he is seen wearing a leather jacket, sunglasses and has his hair slicked back. Jaw then shapes his chin into three large prongs, in order to change his appearance.
Uda is typically a peaceful, easygoing man. He gets nervous under pressure and cries easily. He is never shown to be negative or angry. He is very talkative and is usually seen smiling.
He has shown to be an understanding character, as he was willing to kill the parasite that infected Shinichi's mother, wanting to spare him the burden of killing her.
Uda's wife left him one year after their marriage. Uda contemplated suicide by jumping off a cliff, but could not bring himself to do it. Jaw attacked him and he became frightened and backed up off the cliff into the ocean. Jaw originally followed his instinct to take over the brain, but realized as they were sinking that if Uda drowned, he would die as well. He then abandoned his plan to take over the brain and instead took over Uda's jaw in order to save Uda and therefore himself.
Uda is first seen and mistaken by Shinichi as the parasite that took over his mother's body. This is quickly cleared as Migi informs Shinichi of Uda's situation, and as Jaw, who is known as the Parasite, makes his appearance. Uda and Shinichi soon become friends and bond over each others recent tragedies. Uda decides to help avenge Shinichi mothers death. Back in the city, Uda and parasite make contact with the parasite and inform Shinichi that they're going to a different location.
Now in the woods, Uda and Parasite try to come up with a plan. Due to Uda being overweight, he quickly becomes tired and goes with the plan of standing their ground. Bringing the fight to a cliff, the parasite catches up with them and begins combat. Though holding their own in the beginning, the awkward position in which Parasite is located in his body, soon left them at a disadvantage. The parasite then proceeds to stab Uda in the chest, causing him to fall off the cliff.
As Shinichi is taken aback during his fight with his mother, Uda and Parasite (Jaw) decapitate the parasite. As Uda climbs back up the cliff, Parasite (Jaw) reveals that by shifting the position of Uda's internal organs, he managed to stop any serious damage. Uda then tells Shinichi, that even though it was his mother, he doesn't think he should be the one to finish her off. Uda and Shinichi then say their goodbyes, and say that they'll keep in touch.
After the hair pulling trend becomes popular, Uda is seen having his hair pulled by his employer, making sure he wasn't a parasite. After his boss leaves, Jaw comes out and warns Uda that he needs to be more cautious than ever.