Yūma Chidori is a young woman with waist-length or longer black hair styled in a hime cut featuring blunt bangs. Her grey eyes exhibit a tareme shape, conveying a drooping appearance. She stands 165cm tall with a slim, pale physique and measurements of 83-56-87cm, including a C-cup bust. Her typical attire consists of practical clothing like ankle socks, sports shoes, trousers, and shirts, occasionally accessorized with a necklace; scenes also depict her in partial nudity including bras and panties.

She attends university as a classmate of protagonist Hosaka Ippei, having known him since high school, where peers regarded her as beautiful and popular. Her personality is explicitly honest. Within the narrative, she proactively visits Ippei's workplace to apply for membership, then asks him on a date. This occurs under Sally's influence, who claims supernatural insight into hidden desires and identifies Chidori as harboring a rape fetish.

The date culminates in Ippei sexually assaulting her in a park while disguised with a mask and glasses, though he wears unchanged clothing from their earlier encounter. Ambiguity persists regarding her recognition of Ippei beneath this disguise. Her reactions during and after the assault remain unexplored in documented sources.