Obanai was the first male born into the Iguro family in 370 years, a lineage where only females were born. Perhaps because of this, Obanai spent his childhood with his hair tied like a girl's and wearing a female kimono. The family worships a snake demon with a woman's appearance. They live in luxury by stealing the valuables of those the demon kills, in exchange for sacrificing one of their own infants to the demon. After his birth, Obanai was raised locked in a cage until he was 12 years old. It is said he could hear something crawling on the ceiling every time he tried to sleep.

He is characterized by pale skin, layered semi-long black hair, snake-like eyes, and heterochromia. His mismatched eye colors are natural, with the right eye being yellow and the left eye being blue. There are many mentions of his eyes being beautiful, which was the reason the snake demon took a liking to him. However, his right eye suffers from severe low vision, causing him significant difficulty.

The snake Obanai met while living in the cage.