Nogi Sonoko is one of the three main characters of the light novel Washio Sumi is a Hero. At the time of the story taking place, she's an elementary school 6th-year student chosen by Taisha to fight Vertexes as a Hero, along with Minowa Gin and Washio Sumi.
~!She first appears in the anime in Yuuki Yuuna is a Hero when she summons Tougou and Yuuna after their battle with Vertexes in Episode 8. She had lost the use of most of her body due to the events of Washio Sumi is a Hero and is confined to a hospital bed.!~
~!After being healed of her Sange, she enrolls in Sanshu Middle School and joins the Hero Club as an official member.!~
(Source: Yuki Yuna is a Hero Wiki)