Akechi Eimi is a freshman in First High School, in the same year as the Shiba siblings. She is one of the representative of their school for the Newcomers' Division of the Nine Schools Competition in the events Ice Pillar Break and Speed Shooting.
Her full name is Amelia Eimi Akechi Goldie and often referred to as Eimi.
(Source: Mahouka Koukou no Rettousei Wiki)