Shingo Izumi (泉 信吾,Izumi Shingo) is Hina's older brother, a police detective who is investigating the Greeed and mortally wounded during the attack by the Kamakiri Yummy. His half dead body is then reanimated by Ankh and used as the Greeed's temporary vessel.
Shingo first appeared after a wall of the Kougami Art Museum collapsed and Eiji Hino was seen in his underwear. Shingo questioned Eiji about a few things, until Eiji went on with his life. Shingo appears again intervening the attack of the Kamakiri Yummy and is mortally wounded.
Eiji uses the gun Shingo had on him to help Ankh until he transformed into Kamen Rider OOO to defeat the Yummy and Ankh takes control of Shingo's body, with his hair spiking up and becoming a dull blonde. Whenever Ankh is removed from Shingo, he returns to normal but barely alive, so Ankh must support him to live.
Though he originally needs Ankh to keep him alive, and is able to experience everything the Greeed does through him, Shingo manages to sufficiently recover over time and is fully conscious by the time Ankh is absorbed by his other half. Though a completely healed Shingo intends to help Eiji, he is forced into becoming Ankh's host again after Ankh revives.
After the end of the Greeed conflict, he resumes his work as a police detective.
He will frequently appear every time Ankh leaves the body. This happens in most movies and specials.