Quick answer — Youko Hikasa worked on Encouragement of Climb Season 2 (Theme Song Performance), Seitokai Yakuindomo Season 2 (Insert Song Performance), WWW.WAGNARIA!! (Theme Song Performance) and 13 more anime.
Youko Hikasa worked on Encouragement of Climb Season 2 (Theme Song Performance), Seitokai Yakuindomo Season 2 (Insert Song Performance), WWW.WAGNARIA!! (Theme Song Performance), High School DxD NEW (Theme Song Performance), Inu X Boku Secret Service (Theme Song Performance), Majestic Prince (Theme Song Performance), Ro-Kyu-Bu! SS (Theme Song Performance), IS: Infinite Stratos 2 - Hitonatsu no Omoide (Theme Song Performance) and 8 more.