Quick answer — Yoko Hikasa performed 1 anime theme, including "Utsukushiki Zankoku na Sekai" from Attack on Titan.
Yoko Hikasa performed the anime theme songs "Utsukushiki Zankoku na Sekai" (Attack on Titan).
Yoko Hikasa's first listed anime theme is "Utsukushiki Zankoku na Sekai", the ending of Attack on Titan.