Quick answer — Hiroshi Hiroyama worked on Fate/kaleid liner Prisma☆Illya: Vow in the Snow (Original Creator), Fate/kaleid liner Prisma☆Illya 3rei!! (Original Creator), Fate/kaleid liner Prisma☆Illya: Licht Nameless Girl (Original Creator) and 11 more anime.
Hiroshi Hiroyama worked on Fate/kaleid liner Prisma☆Illya: Vow in the Snow (Original Creator), Fate/kaleid liner Prisma☆Illya 3rei!! (Original Creator), Fate/kaleid liner Prisma☆Illya: Licht Nameless Girl (Original Creator), Fate/kaleid liner Prisma☆Illya 2wei! (Original Creator), Fate/kaleid liner Prisma☆Illya 2wei! Herz! (Original Creator), Fate/kaleid liner Prisma☆Illya (Original Creator), Fate/kaleid liner Prisma☆Illya 2wei! OVA (Original Creator), Fate/kaleid liner Prisma☆Illya: Sekka no Chikai - Kuro Sakura no Heya (Original Creator) and 6 more.