Mini Yaemori is a supporting character in Rent-A-Girlfriend. She is a spirited first-year student at Nerima University and a junior to Kazuya Kinoshita and Chizuru Mizuhara. She moves into the apartment next door to Kazuya, Room 202, and quickly becomes a notable presence in his life. Mini is a YouTuber, streamer on Nicolive and Twitcasting, and an avid cosplayer. She has a slim, petite build with a moderately sized bosom, long black hair with two blue streaks, straight cut bangs, a small cowlick, red eyes, and a distinctive sharp fang. Her casual attire is usually an oversized shirt and shorts with a track jacket, while in public she dresses more femininely, and her room is packed with cosplay clothes and accessories.

Mini has an optimistic and rather childish personality. She is highly curious and often acts on impulse, getting caught up in the moment and speaking bluntly, sometimes to the point of being slightly rude. Despite this, she is fundamentally kind and respects others' boundaries, promising not to pry into their personal affairs unless necessary. She uses a unique speech style, ending her sentences with ssu, which adds to her quirky charm. Her motivations center around her passion for cosplay and connecting with her online audience; she dedicates much of her time to creating content and engaging with fans.

Her role in the story is that of a catalyst and confidante. After accidentally discovering the rental arrangement between Kazuya and Chizuru, she enthusiastically takes on the role of a matchmaker, playfully calling Kazuya her master and using her social media and marketing savvy to support their film crowdfunding project. She provides comic relief with her energetic antics and helps push the main couple forward by offering advice and perspective. She also acts as a bridge between Kazuya and the other characters, often diffusing tense situations with her lightheartedness.

Key relationships include her neighborly bond with Kazuya and Chizuru. She develops a close friendship with both, becoming someone they can confide in. She is also acquainted with Ruka Sarashina, initially mistaking Kazuya for a playboy when she learns about the rental girlfriends. Mini’s development is gradual; through her interactions with the main cast, she gains a deeper understanding of friendship, ambition, and the complexities of love beyond her online persona. Her notable abilities lie in her adeptness at cosplay, content creation, and navigating internet culture, which she uses to support her friends and her own career. She has no supernatural powers, but her creativity, social intelligence, and persistent optimism make her an effective and memorable supporting figure.