Natsumi uses her transformation powers to impersonate Shido at school, performing various "naughty" or offensive acts to turn his friends and teachers against him.
After Shido inadvertently sees Natsumi's "secret," she vows to destroy his life, initially by impersonating him to ruin his reputation and later through a "guessing game". English Dub Cast Date A Live III (Dub) Episode 1
Tohka and Origami are able to distinguish the real Shido from the impostor, forcing Natsumi to retreat. Natsumi uses her transformation powers to impersonate Shido