Quick answer — Aimer performed 4 anime themes, including "Brave Shine" from Fate/stay night: Unlimited Blade Works 2nd Season, "escalate" from NieR:Automata Ver1.1a, "Fate/stay night Aimer - Brave Shine" from Fate/stay night: Unlimited Blade Works.
Aimer performed the anime theme songs "Brave Shine" (Fate/stay night: Unlimited Blade Works 2nd Season), "escalate" (NieR:Automata Ver1.1a), "Fate/stay night Aimer - Brave Shine" (Fate/stay night: Unlimited Blade Works), "Torches" (Vinland Saga).
Aimer's first listed anime theme is "Brave Shine", the opening of Fate/stay night: Unlimited Blade Works 2nd Season.
