Mei Sagara (嵯峨良 芽依/Sagara Mei) is one of the heroines of the Kono Naka ni Hitori, Imouto ga Iru! series.
Mei normally appears as a cheerful girl with a mischievous side.
Regarding Shougo Mikadono, Mei was fond of him and usually called him "Onii-chan" (though unlike other girls who surround Shougo, Mei's feeling for him seems purely platonic.) However, underneath Mei was skeptical of Shougo as a person, and he only earned her respect after he had proven that Mei had been deceiving him.
A third-year silver-haired bespectacled girl who dresses as a witch. She runs the Lyrical Sister Café which she describes as "a dream-like café where anyone can become an older brother or older sister!" Prior to the story, her biological parents abandoned her as a toddler because of her mathematical intellect and she was adopted by a university professor. She lived with her adoptive mother who owned and ran the café until she died. Afterwards Mei lived with her father in Massachusetts until she earned enough money to buy back the café. She and Konoe have the same brand phone. It is later revealed that she knows the identity of Shogo's sister, but does not want to expose her to the Mikadono family because she is an illegitimate child. After Shogo promises to protect her, she responds that she will reveal his sister's identity if he proves that he can be a good older brother.