I really didn't know much about her so here's a short July 16th article from Nihongogo.com:
Iori Sagara Makes Her Debut as Member of Nogizaka46Iori Sagara stunned the crowd at Roppongi’s Tokyo Blue Theater as she joined her fellow members of Nogizaka46 on stage with their rendition of Valletta.
The 16-year old understudy, last seen on stage on June 14th for 16nin no Principle Trois, returned to the group after her school semester and the crowd was eager to welcome her with open arms. Fans at the theater cheered wildly before Sagara even stepped on stage with her voice filling the concert hall during the introduction of Valletta.
Sagara participated in seven songs and was in tears by the epic finale. This is the first concert Sagara has participated in as a member of Nogizaka 46, and by the cheers from the crowd, they wouldn’t want it to be her last.
Plus here's her promo video for volume 3 of Nogi46 Quarterly.