Haya Nonohara is a cheerful, lighthearted individual who often refers to herself in the third person as "Non," embodying a playful and airheaded charm. She works part-time at Narazuya Cafe alongside the protagonist, where her whimsical secrecy and comedic antics enliven the atmosphere. Her loyalty shines in interactions with close friends Karin Hanamatsuri and Kanata Kurosu—models connected to the cafe—highlighting her steadfast support for those she cherishes.

During the OVA’s central romantic conflict, Haya steps into a pivotal supportive role. When Inori visits a festival alone due to her boyfriend Isshu’s absence, Haya partners with Shizuru Shirakawa to nudge Isshu toward prioritizing his relationship, culminating in a heartfelt reconciliation amid the fireworks. This moment reveals her intuitive grasp of others’ emotions and a proactive kindness that contrasts her usual carefree persona.

Her design features waist-length orange twintails tied with ribbons, bright yellow eyes, and a maid-inspired uniform complete with a headdress, aligning her visually with energetic genki archetypes. While her personality and role adhere to these tropes, the available narrative does not delve into her personal history, family, or expanded development across other media.