Yuuki Yuuna Is a Hero

Season 2, Episode 7: Brilliant Days

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Following their battle against the Vertex, YUuna, Fuu, Itsuki, and Karin are joined by a fully recovered Sonoko as the Hero Club resumes its normal activities. However, Yuuna starts to get a strange feeling that someone is missing from the equation. The next day, upon experiencing more deja vu, both Yuuna and Sonoko come to the realization that someone has altered their memories to make them forget all about Tougou, as if she never existed. Upon recalling their true memories of Tougou, who had been taking up a masked hero persona to make up for her sins, the girls are left with the question of where she has disappeared to.