Natsumi sends Shido a letter with 12 photos of people close to him. She reveals she has replaced one of them and challenges him to identify the impostor before they all "disappear".
Tohka and Origami are able to distinguish the real Shido from the impostor, forcing Natsumi to retreat. Date A Live III (Dub) Episode 1
During an AST attack, Natsumi's true form is briefly exposed. Believing Shido has seen her "secret" (her true, insecure appearance), she becomes hostile. Natsumi sends Shido a letter with 12 photos