Okumura appears to be an older man with unkempt hair and a full beard. He is tall ad despite living on the streets, he is seemingly still fit enough to consider returning to work as an exorcist.
Whilst travelling in the past, Rin Okumura observes the life of his mother, Yuri, before she joined the True Cross Order. He watches Yuri live and play in the junkyard before a tragic fire kills Oku, Obaba and Niko, forcing Yuri into the streets alone.
It is later revealed to Shiro Fujimoto by Satan that Oku's death was not an accident, the fire being a result of his attempts to possess Oku, Niko and Obaba. However, Oku decided to kill himself in order to save Yuri.