Rio Hanamura is a third-year student and member of the Momomi Futsal Club, where he plays as the pivot. He proudly claims the title of Warunori lover No. 3. Rio constantly floods his social media feed, earning the label "SNS holic" for regularly uploading photos taken by others to "Peasta." A self-proclaimed trend enthusiast ("meha"), he gravitates towards new, fashionable items and possesses a distinct fondness for cute things. His outwardly flirtatious nature contrasts with a perceptive understanding of group dynamics. He demonstrates genuine concern for teammate Yukimaru Kurama, who is often overlooked. Rio frequently engages in teasing club captain Nozomi Komori alongside teammates Natsuki Sogo and Kyosuke Aiba.

Academically, English is his preferred subject. He balances studies with a part-time job at a café. His hobbies include updating his social media presence and collecting sneakers. Rio possesses impressive athletic speed, clocking 100 meters in 11 seconds. He enjoys idol anime and snack foods, while disliking strict environments and the taste of coriander. His family consists of parents and two older sisters, one named Rii; he regards his sisters with apprehension, describing them as "scary." He is commonly known by the nickname "Rio." The kanji in his given name "Rio" mean "reason, logic" (理) and "center" (央), while his surname "Hanamura" combines "flower, blossom" (花) and "town, village" (村).