Noriko Mizushima

Fourth grade, St. Miator. Belongs to the school's kyuudou club.
Nagisa and Tamao's neighbor at Ichigo-sha. She is also their friend, therefore sometimes attends the secret tea parties they are occasionally throwing.

Noriko's roommate, Chihaya Takemura, was her classmate in every school they attended since the very beginning of kindergarten. Since they had been together for roughly 12 years, according to Tamao's calculations, Nagisa compares them to a married couple in episode 3.

(Source: Wikipedia, translated)